Perceived Sound Quality of Reproductions with Different

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Perceived soundquality of reproductions with different frequency responsesand sound levels AIf Gabrielsson Departmentof TechnicalAudiology, Karolinska Institute, Stockholm, and Department of Psychology, UppsalaUniversity, Uppsala, Sweden BjOrn Hagerman,Tommy Bech-Kristensen,and GOran Lundberg Departmentof TechnicalA udiology,Karolinska Institute, K TH, S-10044 Stockholm,Sweden ( Received27 February1989; accepted for publication6 April 1990) Threeprograms (female voice, jazz music,and pink noise)were reproduced using four differentfrequency responses and two differentsound levels. Fourteen normal hearing subjects listenedto the reproductionsvia carphonesand judged the soundquality on sevenperceptual scales(loudness, clarity, fullness,spaciousness, brightness, softness/gentleness, and nearness} and a fidelity scale.Significant differences among the reproductionsappeared in all scalesand couldbe attributedto the differencesin frequencyresponse or soundlevel or both. Interactions betweenthe reproductionsand the programscould be explainedby the relationsbetween the spectrumof the programsand the frequencyresponses used. The resultsfor the noiseprogram weresimilar to thosefor thejazz musicprogram. PACS numbers:43.66.Lj, 43.88.Md [NFV]

INTRODUCTION crease(dullness and softness/gentlenessdecrease) with ris- ing frequencyresponse toward higher frequenciesand/or The perceivedsound quality of sound-reproducingsys- falling responsetoward lower frequencies(cf. alsoStevens tems-such as loudspeakers,headphones, and hearing and Davis, 1938,pp. 163-166, for densityand brightnessin aids--is multidimensional;that is, it is associatedwith a sinusoidaltones; Bismarck, 1974). Fullnessis favoredby a numberof perceptualdimensions. By meansof multivariate broadfrequency range and relatively more emphasis on low- methodsused in experimentalpsychology, we wereable to er frequencies(cf. Stevensand Davis, 1938,p. 161,for vol- showthat the perceivedsound quality can be describedin ume in sinusoidaltones). Clarity, spaciousness,and (to termsof dimensionssuch as clarity, fullness, brightness ver- someextent) nearnessare likewisefavored by a broad fre- susdullness, sharpness versus softness/gentleness, loudness, quencyrange, often with a certainemphasis on midhighto spaciousness,nearness, and absenceof extraneoussounds highfrequencies. The effectsof extraneoussounds, e.g., hiss, (Gabrielsson,1979a; Gabrielsson and Sjfigren, 1979a). Rat- may be relievedby reducedresponse at high frequencies. ing scalesfor thesedimensions have beensuccessfully used Generally,the resultsalso depend on the characteristicsof to provideperceptual descriptions of loudspeakersand other the (musicor speech)programs that are reproduced.There sound-reproducingsystems (Gabrielsson and Lindstr/Jm, are thusinteractions between the reproductionsystems and 1985; Gabrielsson,1987; Gabrielssonet al., 1988). Overall the programs. evaluationsof thesystems in termsof fidelityor pleasantness Another importantphysical factor is the soundlevel. may be regardedas weightedcombinations of the separate The availableevidence (e.g., Gabrielssonand Sj/Sgren, perceptualdimensions. The weight given to each dimen- 1979a) indicatesthat an increasein soundlevel will usually sion-that is, how important it is for the overall evalua- increasethe perceivedfullness, spaciousness, and nearness tionsdependson the characterof the programto be repro- aswell as sharpness and brightness; a decrease in soundlevel ducedand the listener'searlier experiences. givesthe oppositeresults. Increased sound level may also The relationsbetween the perceptualdimensions and contributeto increasedclarity, althoughonly up to a certain variousphysical properties of the systemsare complexand level at which overloadingin the auditory systemmay occur still largely unknown.Among the physicalvariables the fre- (Kryter, 1970, p. 52). There may be interactionsbetween quencyresponse is often consideredas the mostimportant. the soundlevel, on the one hand,and the frequencyresponse Its effectson the perceptualdimensions have been explored and/or the spectrumof the programon the other hand.For in a posthoc manner by studyingthe frequencyresponse of instance,a programreproduced by a systemwith boosted the systemsreceiving different ratings in the respectivedi- treblemay soundeven sharper and brighter if the soundlevel mensionsand alsomore directly by experimentalmanipula- is increased,while a reproductionwith boostedbass will tion of the frequencyresponse (Gabrielsson et al., 1974;Ga- probablysound even duller if the soundlevel is raised. brielssonand Sj/Sgren,1979a,b; Gabrielsson et al., 1986, Becauseof suchcomplex interactions and alsobecause 1987, 1988;cf. alsosimilar approachesby Komamura eta/., of theposthoc character of certainresults referred to above,a 1977; K/Stter, 1968; Staffeldt, 1974; Toole, 1986; Toole and further experimentwith systematicmanipulation of the fre- Olive, 1988). The resultsof our investigationsindicate that quencyresponse and the soundlevel was conducted.The the frequencyresponse can affect any of the above-men- purposewas to investigatethe effectson the perceptualdi- tionedperceptual dimensions. Brightness and sharpnessin- mensionsof four markedly differentfrequency responses

1359 J. Acoust.Soc. Am. 88 (3), September1990 0001-4966/90/091359-08500.80 @ 1990 AcousticalSociety of America 1359 (flat, boostedat low, midhigh,and high frequencies)and before binaural (diotic) presentationto the listeners two differentsound levels in the reproductionof threepro- through Sony Walkman MDR-E262 earphones.The fre- gramsincluding speech, music, and pink noise. quencyresponse of the earphonesis shown in Fig. 2. The steepcutoff at about6 kHz isdue to the antialiasinglow-pass I. METHOD filter described below. A. Programs The filterswere implemented as digital FIR filtersusing a generalpurpose measuring device (TAMP3) developedin Three programswere used:(1) pink noise( -- 3 dB/ our department.It can be usedfor measuringthe frequency oct), monophonicrecording; (2) femalevoice readinga responseof linear,time-invariant systems and also for digital fairy-talein an anechoicchamber, monophonic recording; filteringof signalsin real time. It is equippedwith antialias- and (3) jazz music, excerpt from "Ole Miss" by W. C. ing filtersand fast 12-bit A/D and D/A converters.Various Handy, performedby The Peoria Jazz Band in an auditor- typesof input amplifiers,output amplifiers, and attenuators ium. Phonographrecord: Opus 3, 79-00, Testskiva1: Per- canbe connected to the processor.All unitsare controlled by spektiv.The excerptwas copieddirectly from the stereo- a personalcomputer. phonicrecording on the mastertape, but was played The samplingfrequency of the digital filter had to be monophonically.to the listener. restrictedto 20 kHz, and an antialiasinglow-pass filter was Each programlasted for about 1 min. The pink noise setto 6.7 kHz. Four differentfilters were implemented. One was chosen to serve as a neutral reference. The female voice filter had a flat response,that is, no filteringat all. The other in the anechoicchamber has most of its energybelow 1 kHz, three filters gave about 9 dB amplificationbelow 200 Hz, especiallybetween about 130 and 700 Hz, while the jazz around 1 kHz, and around4 kHz (seeFig. 3). (The lowest music has a considerablybroader frequencyrange With a filter couldnot be madesymmetrical because of certainlimi- boostaround 100 Hz (seeFig. 1). The programswere low- tationsin the equipment.Below 100 Hz thereis little energy passedat 6.7 kHz for reasonsexplained below. due to the cutoffof the earphones;cf. Fig. 2.) Thesefilters will be referredto as the L (for low), M (midhigh), and H B. Reproduction system (high) filter, respectively. A tape recorder (Telefunken Magnetophon28) was The soundlevels were set to representan approximately usedto reproducethe programs,which were then filtered natural level of the respectiveprogram when listenedto in the earphonesthrough the filter with fiat response.Mea- suredby a coupleraccording to IEC 711 fitted into the KE- MAR manikin, the A-weightedsound level for the pink noisewith the fiat responsewas about 68 dB, for the female { 10dB voiceabout 56 dB, and for thejazz musicabout 80 dB. For comparisoneach program was also presentedat a l0 dB lower level. The filtersthemselves caused certain changes in the o,zo 0.5(] 2.oo 5.o({ 0.1 1.o soundlevel. These effects were different for differentpro- kH• gramsdepending on their spectrum(Fig. l ). For the pink noisethere was practically no differencein the A-weighted soundlevel betweenthe fiat responseand the L filter, while the M filter gave an increaseof 2 dB, and the H filter an voice increaseof 6 dB. For thejazz musicthere was again no differ- i 10dB encein the A-weightedsound level between the fiat response and the L filter, while the M filter gavean increaseof about$ dB and the H filter an increase of about 3 dB. For the female

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kHz kHz FIG. 1. Long-timeaverage spectrum (LTAS) for the threeprograms. LTAS wascalculated from the autocorrelation function of theprogram and FIG. 2. Frequencyresponse of the earphonemeasured on a manikin (KE- smoothed across octaves. MAR) equippedwith an earsimulator according to IEC 711.

1360 J. Acoust.Soc. Am., Vol. 88, No. 3, September1990 Gabrielssonat a/.: Perceivedreproduction quality 1360 o 2 3 q 5 G ? 8 9 IO I 5d8 •...... • ...... • ...... • ...... • ...... , ...... •...... •...... • ...... J...... , LOUUNESS o 2 3 5 G 7 8 9 I0

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E. Design and procedure about 3 dB, the M filter about 2 dB, and the H filter about 1 dB. Theseeffects have to be consideredin the interpretation There were 24 conditions(three programsX four fil- of the results. tersX two soundlevels), and they were rated twice by each The listener was seated in a sound insulated chamber subjecton all eightscales (however, the noiseprogram was usedfor psycheacousticexperiments. All equipmentand the ratedon seven scales omitting the fidelity scale). The presen- experimenterwere in an adjoiningroom. tation order of the stimuli was randomizeddifferently for eachsubject. The orderof the ratingscales on the response C. Subjects form (Fig. 4) wasalso randomized differently for eachsubject.After introducingthe subject to thesituation and trying Fourteensubjects, seven males and sevenfemales, age out the earphones,the instructions(Appendix) were given, 22-34 years,participated. None of themhad any experience followedby 12 practicetrials. Then the main experiment in thistype of experiment.All of themwere tested for normal including48 trials (24 stimuliX2 trials per stimulus)was hearing (lessthan 20-dB hearing loss,250-8000 Hz, ISO conductedwith a breakin the middle.After that, the subject 389). answeredsome questions related to the experiment. The positionof smallearphones is criticalfor the result- D. Response variables ing frequencyresponse at the eardrum.In order to check The reproductionswere rated on eightscales. Seven of that the earphoneswere placed in a similarway for the two them refer to perceptualdimensions: loudness (Swedish: partsof the mainexperiment (before and afterthe break), a ljudstyrka), fullness(fyllighet), brightness(ljushet), soft- broadbandsignal was used, and the resultingresponse was ness/gentleness(mjukhet), nearness(n•irhet), spacious- measuredby a Diaphonprobe microphone inserted into the ness(rymdk[insla), and clarity (tydlighet). The eighthscale ear canal behind the earphone.The microphoneresponse requiredan overallevaluation of eachreproduction in terms wasfed intoTAMP3 for analysisof the frequencyresponse. of its fidelity.All scaleswere gradedfrom 10 (maximum) to On the whole,these frequency responses were fairly similar 0 (minimum) and with definitions for 9, 7, 5, 3, and 1 as seen in both parts of the experiment.Between 200 and 3000 Hz, in Fig. 4. Decimals were included, since many subjectsin the differenceswere usually lessthan 2 dB. A dip was often earlier investigationsused decimals in their ratings (Ga- found around 150 Hz, somewhatvarying in positionand brielssonand Lindstrrm, 1985; Gabrielssonet al., 1988). size. Differenceslarger than 5 dB were found around 4-5 Definitionsand further explanationswere given in the kHz in a few cases.The varianceof the repeatedratings for instructions(see the Appendix). eachstimulus (of. Sec.II below) was of the sameorder asfor

1361 J. Acoust.Sec. Am., Vol. 88, No. 3, September1990 Gabrielsson•! a/.: Perceivedreproduction quality 1361 a groupof correspondingsubjects in an earlierexperiment 1971, p. 283; Oabrielsson,1979b). Its maximum value is with supra-auralheadphones (Gabrielsson et al., 1988). 1.00;the higher the value, the better the reliability. As seenin The totaltime required for eachsubject was about 2.5 h. Table I, the reliabilityis againhighest for loudness(0.98), Besidethe necessarytime for the instructions,the practice but isgenerally high (0.84-0.95) for the otherscales as well. trials, and the break, much time was spent in fitting the probemicrophone and the earphone.The actuallistening B. Effects of sound levels time was about 50 min. The effects of the different sound levels can be seen in Fig. 5, whichshows the averageratings across all subjectsin F. Data treatment eachscale for the differentreproductions. In loudnessthe The subjects'ratings were subjected to analysisof vari- ratingsat the highsound level arc 1.5-3 unitshigher than for ance,separately for eachscale. This wasdone both for each the correspondingcases at the low level. The differenceis individualsubject (sources of variance:filters, sound levels, highly significant [F(1,13)= 140, p<0.001]. The high and programs;fixed model) and overall subjects(sources: sound level also gives better clarity [F(1,13)=19.8, filters,sound levels, programs, and subjects;mixed model). p < 0.001], more fullness[ F(1,13) = 17.0,p < 0.01], more One-tailedt testswere usedto test specifichypotheses, de- spaciousness[F(1,13) = 35.2, p <0.001 ], more nearness rived from our earlier investigations,concerning the effects [F(1,13) = 95, p < 0.001], and better fidelity of differentfilters. For generalprinciples concerning analy- [F(1,13) = 7.6, p < 0.025 ], but less softness/gentleness sis of varianceand related questions,see Winer ( 1971) or IF(1,13) = 47.2, p<0.001], than the low soundlevel. In Kirk (1982). For applicationin listeningtests, see Gabrids- brightnessthere was no statisticallysignificant difference be- son (1979b). tween the two levels. There is alsoa significantdifference in rated loudness II. RESULTS amongthe programs[F(2,26) = 9.9,p < 0.001], anda sig- A. Reliability of ratings nificant programX level interaction [F(2,26) = 18, The intraindividualreliability was studied by meansof p < 0.001]. The meaningof theseresults is clear from Fig. 5. the "within cell meansquare" (MSw) in the individualanal- At the highlevel the voiceis ratedlower in loudnessthan the ysesof variance,that is,the estimatedaverage variance of the other programs, while there is practically no difference two ratingsmade for eachstimulus in eachscale (MSw is the amongthe programsat the lowerlevel. The perceivedloud- error term for the F tests in the fixed model). The smaller nessis thus reducedmore for the noiseand jazz programs this variance,the better is the reliability. The median value than for the voice, when the sound level is lowered. The fact for MSw overall 14subjects for eachscale appears in Table I. that the noiseis ratedalmost as high in loudnessas the jazz (The median was chosen rather than the arithmetic mean music, althoughthere is a considerabledifference between becauseof oneextremely deviating subject.) MSw is clearly their sound levels,is probably due to the continuousand lowest for the loudnessscale (0.53), which is the most famil- "irritating" characterof the noise. iar dimension. For the other scales MSw varies between 1.27 The effectsof the differentprograms on the other per- and 1.64. These values are about the same as for another ceptualscales are usuallyself-evident and will not be further groupof unselectedsubjects with normalheating described commented. in Gabrielssonet al. (1988), but are higher (that is, the reli- C. Effects of filters ability is worse) than for subjectsselected for experienceof listeningto high-fidelitysound reproduction (Gabrielsson The effectsof the differentfilters are discussedseparate- and Lindstrfm, 1985). Anotherindication of goodreliabil- ly for eachscale. ity is the occurrenceof significantF tests(at 0.05 level or lower) for thedifferent experimental variables. Out of the 14 • Loudness subjects,typically at leasthalf of them had significantdiffer- encesamong the variousfiltered reproductions in eachscale. There is a significantdifference among the various The interindividualreliability (the agreementbetween filters [F(3,39) = 20, p < 0.001] and a significantfilter X le- the subjects)was estimated by meansof the % index (Winer, vel interaction [F(3,39) = 6.2, p < 0.01 ]. As seenin Fig. 5 for the high level,the L, M, and H filtersgive an increasein TABLE 1[.Median valueacross subjects for MSw and valueof the rs index loudnessin comparisonwith the flat response,which may be for each rating a•alc. expectedsince these filters usuallyalso producean increase of the overall soundlevel (cf. Sec.I B). An exceptionis the MSw r• H filter for the voiceprogram; but sincethe voicehas most of its energybelow 1000Hz, it is not muchaffected by the H Loudness 0.53 0.98 Clarity 1.40 0.91 filter (cf. Figs. I and 3). At the low levelthereare similar but Fullness 1.37 0.86 less-pronouncedtendencies. Spaciousness 1.64 0.9 i The fact that the filtersusually give an increasedoverall Brightness 1.27 0.92 Softness 1.27 0.95 soundlevel in comparisonwith the fiat responsehas to be Nearness 1.48 0.93 consideredwhen intcrpretating the resultsin the remaining Fidelity 1.29 0.84 scales. If the results for the different filters arc in the same directionas couldbe expectedfor a highersound level, the

1362 J. Acoust. Soc. Am., Vol. 88. No. 3, September 1990 Gabrielssone! a/.: Perceived reproductionquality 1362 IO LOUONESS LOUONESS SPRC]OUSNESS o..t(.etc•

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situationis ambiguous:The effectmay be due to the respec- Clarity tive frequency response,or to increasedsound level, or to a combinationof both. However, if the resultsgo in the oppo- The averagerating for the L filter acrossall programs sitedirection, or ifa differencein soundlevel has no expected and both soundlevels is 5.0, which is significantlylower than effect, as for brightness,the effect can be attributed to the the corresponding value for the flat response, 5.6 respectivefrequency response. [ t(39): 2.4, p < 0.025]. Further the averagerating for the

1363 J. Acoust.Sec. Am., Vol. 88, No. 3, September1990 Gabrielssonota/.: Perceivedreproduction quality 13G3 H filter (6.2) is higher than for the fiat response 6. Softness/gentleness [t(39) = 2.4, p <0.025]. The differencebetween the M fil- Although the differencebetween the L filter and the flat ter and the fiat responseis not significant.The betterclarity responsedoes not quite reach statistical significance for the H filter maybe dueto its frequencyresponse or to an [t(39) = 1.08,p<0.15], the data in Fig. 5 indicatean in- increaseof the overall sound level, or to both. However, the creasein softnessfor the L filter, which then must be due to worseclarity for the L filter cannotbe attributedto an in- its frequencyresponse (since a possibleincrease in sound creasedoverall sound level (this wouldgive better clarity), levelwould reduce softness). The M filter givesless softness but dependson the increasedresponse at low frequencies. ( = more sharpness)than the flat response[t(39) = 2.74, p<0.005], and so does the H filter [t(39)=3.33, 3. Fullness p < 0.005]. These effectsmay be due to the frequencyre- The L filter givesmore fullnessthan the flat response sponsesof the filters or to the accompanyingincrease in [t(39) = 2.65,p <0.01 ]. There is no differencebetween the overall sound level, or to both. M filter and the flat response.There is a tendency,just short There is a significant levelX filter interaction of statisticalsignificance, for the H filter to giveless fullness [F(3,39) ----5.2,p < 0.01 ], meaningthat the decreaseof soft- thanthe flat responseat the highersound level, especially for nesswith the M and H filters is more pronouncedat the the noiseand jazz programs.The last-mentionedeffect can- higherlevel than at thelower (seeFig. 5). In our ownexperi- not be due to an increased overall sound level associated with ence,the noise and the jazz musicsound sharp and irritating, the H filter, since this would increasefullness. The reason is when reproducedby the H filter at the high level.There is probably that the H filter makes the lower frequencies, also a significant filter X program interaction which contribute most to fullness,less important. For the [F(6,78) ----6.5, p < 0.001]. While the noiseand jazz music voiceprogram the effectof the H filter is small,since most of soundssharpest with the H filter, the voiceprogram sounds its energylies below the rangeof the H filter.The increased sharpestwith the M filter (see Fig. 5). The H filter cannot fullnessfor theL filtermay depend on its frequency response contributevery much to sharpnessin the voiceprogram, or on an increaseof the overall soundlevel, or on both. How- sinceit only affectsfrequencies above the main part of the ever, sincethe increasein overall soundlevel is larger with voicespectrum. the H and M filters than for the L filter (cf. Sec. I B), and since there is no difference or even a decrease in fullness for 7. Nearness the H and M filters, the increased fullness for the L filter The noiseand jazz programstend to soundnearer for all mustbe an effectof its frequencyresponse. threefilters, especially at the higherlevel, whereas this does not hold for the voiceprogram. The differencebetween the M filter and the.flat responseacross programs and levelsis dose to significance[ t(39) = 1.64,p < 0.10 ]. This may be 4. Spaciousness due to its frequencyresponse or the concomitantincrease of Spaciousnessis significantlylower for the L filter than the sound level or both. for the fiat responseacross programs and sound levels [ t(39) = 1.72,p < 0.05]. (However,there is no difference 8. Fidelity for thejazz programat the lowersound level.) This effectis As seenin Fig. 5, the fidelityis consistentlyworst for the dueto the frequencyresponse of the L filter,since a possibly L filter,and the differencebetween the flat responseand the increasedoverall level would lead to morespaciousness. L filter is highly significant[t(39)= 3.84, p<0.0005]. However, there is also an interaction between sound levels andfilters [F(3,39) ----4.7, p <0.01 ]. The differencesamong 5. Brightness the filters are much more evidentat the higher, natural sound level than at the lower level. At the lower level the Sincethere was no differencein brightnessbetween the only clear resultis that the L filter is worsethan the others. two soundlevels, any differencebetween the filtersis due to However,at the higherlevel the L, M, and H filtersare all differentfrequency responses. The L filter reducesbright- ness throughout, and the differencebetween the flat re- worsethan the flat response.Since fidelity thus becomes sponseand the L filter acrossprograms and soundlevels is worsewith those filters, despite their accompanying increase of the overall sound level, these results are due to the fre- highly significant [t(39) = 6.04, p<0.0005]. The H filter increasesbrightness, and the differencebetween the H filter quencyresponses of the respectivefilters. and the flat responseis alsohighly significant[ t(39) = 3.04, Earlier resultsindicate that a slightor moderateempha- p < 0.005]. There is no significantdifference between the M sis on midhigh to high frequenciesis favorableto fidelity filter and the flat response,but there is a tendencytoward (Gabrielssonand Sj/Sgren,1979a; Gabrielsson etal., 1988). higherbrightness for the M filter at the highersound level. However,the presentM and H filtersrepresent too pro- The differencebetween the H filter and the flat response nouncedboosts (about 9 dB) and make fidelity worse. is much smaller for the voice program than for the other III. DISCUSSION programs.The reasonis that the H filter doesnot influence the voice program very much, sinceits effectlies mainly Themanipulations of thesound level and the frequency outsidethe spectrumof the voiceprogram. responseaffected all perceptualdimensions included here.

1364 J. Acoust.Soc. Am., Vol. 88, No. 3, September1990 Gabrielssoneta/.: Perceivedreproduction quality 1364 The resultsmainly agree with what couldbe expectedfrom Clarity: The reproductionsounds clear, distinct,and our earlierinvestigations (see the Introduction). The high- pure.The oppositeis that the soundis diffuse, blurred, thick, er, naturalsound level provided better clarity, more fullness, and the like. spaciousness,and nearness--butless softness/gentleness-- Fullness:The reproductionsounds full, in oppositionto aswell asbetter fidelity than the 10-dBreduced level. There thin. was no differencewith regardto brightness.Use of the L Spaciousness:The reproductionsounds open and spa- filter resultedin morefullness and possiblysoftness/gentle- cious,in oppositionto closedand shut up. ness,but lessclarity, spaciousness,and brightness ( = more Brightness:The reproductionsounds bright, in opposi- dullness),and worsefidelity than with the flat response. tion to dull and dark. Theseeffects can all be attributedto the frequencyresponse Softness/gentleness:The reproductionsounds soft and of the L filter. The M filter gave less softness( = more gentle,in oppositionto sharp,hard, keen,and shrill. sharpness)than the flat response,which may be due to its Nearness:The soundseems to be closeto you, in opposi- frequencyresponse or to an accompanyingincrease in the tion to at a distance. overallsound level, or to both. The M filter alsogave worse Loudness:The sound is loud, in oppositionto soft fidelity at the higher, natural soundlevel than the flat re- (faint). sponse.This effectis due to its frequencyresponse. The H Fidelity:Judge how similar the reproductionis to the filter resultedin betterclarity and morebrightness, but less originalsound. 10 = perfectfidelity, 9 = verygood, 7 = softness( = more sharpness)and possiblyfullness; and rathergood, and so on. (This scaleis not usedfor thenoise.) worsefidelity at the higher,natural sound level than the flat There is a new responseform for each reproduction. response.The effectson brightness,fullness, and fidelityare Mark yourjudgment on eachscale by a straightvertical line. dueto its frequencyresponse, while the effectson clarity and Do your ratingson eachscale without lookingat the other softnessmay dependon its frequencyresponse or on the scalesor earlierresponse forms. There are no right or wrong accompanyingincrease of the overall sound level, or on answers.It issolely your opinion about the sound that should both. be decisive. Therewas often an interactionbetween filters and pro- gramssuch that the effectof the H filter wasdifferent for the voiceprogram than for the otherprograms, probably due to the restrictedfrequency range of the voiceprogram. There Bismarck,G. yon (1974). "Sharpnessas an attributeof the timbreof steady sounds," Acustica 30, 159-172. werealso interactions with the soundlevels, meaning that Gabrielsson,A. (1979a). "Dimensionanalyses of perceivedsound quality theeffects of thefilters and/or thedifference among the pro- of sound-reproducingsystems," Scand. J. Psychol.20, 159-169. gramswere more pronounced at the highersound level than Gabrielsson,A. (1979b). "Statisticaltreatment of data from listeningtests at the lower; seethe resultsfor loudness,fullness, softness, on sound-reproducingsystems," Tech. Audiel. Rep. No. 92 (Karolinska Institute, Stockholm). and fidelity in Fig. 5. Gabrielsson,A. (1987). "Planningof listeningtests: Listener and experi- Interestingly,the resultsfor the "neutral" noisepro- mentalvariables," in Perceptionof ReproducedSound, edited by S. Bech gramare verysimilar to thosefor thejazz musicprogram as and O. J. Pedersen(Technical Universityof Denmark, Copenhagen), seenin Fig. 5. Thosetwo programsare alsorather similar in pp. 51-60. Gabrielsson,A. and Lindstr6m,B. (1985). "Perceivedsound quality of their long-termaverage spectrum. high-fidelityloudspeakers," J. Audio Eng. Sec.33, 33-53. Gabrielsson,A., Lindstr6m,B., and Till, O. (1986). "Loudspeakerfre- ACKNOWLEDGMENTS quencyresponse and perceived sound quality: Measurements in listening room," Tech. Audiel. Rep. No. 114 (Karolinska Institute,Stockholm). We wishto expressour gratitudeto Ove Till and to our Gabrielsson,A., Lindstr6m,B., and Till, O. (1987). "Loudspeakerfre- subjects.This work was supportedby The Bank of Sweden quencyresponse and perceivedsound quality: Comparison between mea- surementsin listeningroom, anechoicroom and reverberationroom," Tercentenary Foundation and the Swedish Ministry of Tech. Audiel. Rep. No. 115 (Karolinska Institute,Stockholm). Health and Social Affairs, Commission for Social Research. Gabrielsson,A., Rosenberg,U., and Sj6gren, H. (1974). "Judgmentsand dimensionanalyses of perceivedsound quality of sound-reproducingsystems," J. Acoust. Sec. Am. 55, 854-861. APPENDIX Gabrielsson,A., Schenkman,B. N., and Hagerman,B. (1988). "The effects 1. Instructions of differentfrequency responses on soundquality judgments and speech intelligibility,"J. SpeechHear. Res.31, 166-177. You are going to listen to variousreproductions of Gabrielsson,A., and Sj6gren,H. (1979a). "Perceivedsound quality of speech,music, and noisethrough earphones. Your taskis to sound-reproducingsystems," J. Acoust. Sec. Am. 65, 1019-1033. Gabrielsson,A., and Sj6gren,H. (1979b). "Perceivedsound quality of judge the soundquality of the different reproductionsby hearingaids," Scand.Audiel. 8, 159-169. meansof the scaleson the responseform. The scalesrefer to Kirk, R. E. (1982). ExperimentalDesign: Procedures for the Behavioral variousproperties of the soundreproduction. They are all Sciences(Brooks/Cole, Belmont, CA), 2nd ed. gradedfrom 10 (maximum) to 0 (minimum). For instance, Komamura, M., Tsuruta, K., and Yoshida, M. (1977). "Correlation between subjectiveand objectivedata for loudspeakers,"J. Acoust.Sec. in the scalefor fullness10 meansmaximum (highestpossi- Jpn. 33, 103-115. ble) fullness,9 = very full, 7 = rather full, 5 = midway, 3 Kryter, K. D. (1970). The Effects of Noise on Man (Academic, New = rather thin, 1 = very thin, and 0 meansminimum full- York). K6tter, E. (1968). Der Einfiussuebertragungstechnischer Faktoren auf das ness.The other scaleswork in similar ways.As you can see Musikhbren (Arno Volk, K6ln). onthe response form, it ispossible to usedecimals if youlike. Staffeldt,H. (1974). "Correlationbetween subjective and objective data for The scales are defined as follows. quality loudspeakers,"J. Audio Eng. See.22, 402-415.

1365 J. Acoust.Sec. Am., Vol. 88, No. 3, September 1990 Gabrielssonot •/: Perceivedreproduction quality 1365 Stevens,S.S., and Davis, H. (1938). Hearing:Its Psychologyand Physiology Toole,F. E., andOlive, S. E. (1988). "The modificationof timbreby reson- (Wiley, New York). ances:Perception and measurement,"J. Audio Eng. Soc.36, 122-142. Toole,F. E. (19•6). "Loudspeakermeasurements and their relationship to Winer, B. J. (1971). StatisticalPrinciples in ExperimentalDesign listenerpreferences: Part 2," J. AudioEng. So½. •4, 323-348. (McGraw-Hill, New York), 2nd ed.

1366 J. Acoust.Soc. Am., Vol. 88, No. 3, September 1990 Gabdelssoneta/.: Perceivedreproduction quality 1366