TECHNICAL REPORT Headroom Predictions Using B-Noise in MAPP XT UPQ Pink Noise at 1m: 1/3 Octave Spectrum A Weighted Average = 116 dB Z Peak = 131 dB MAPP Predictions using Pink Noise The Relationship of Headroom to Frequency The equal energy per octave nature of pink noise makes it an Because the linear SPL capability of a loudspeaker is dependent accepted reference source to predict the SPL and headroom on the spectral content of the input signal, measured SPL of a loudspeaker or loudspeaker array. Pink noise is also an values for the same speaker will be different for each type of excellent, albeit conservative, means of estimating the SPL a input. For example, the limited frequency content of speech system would linearly reproduce when driven with other types presents different headroom demands on a loudspeaker than of inputs that have broad spectral content. the broader frequency content of electronic dance music. Therefore, using only full-bandwidth pink noise to predict When pink noise is applied to a Meyer Sound UPQ, the the SPL capability of a system would not expose that system’s resulting headroom curve shows the amplitude the speaker higher potential for linear reproduction of a band-limited input can achieve over the range of audible frequencies before signal. For speech-only systems, decisions based on a headroom limiting at any given frequency. curve derived from a pink noise input could lead to over- specification of the loudspeaker system design. These pink noise-based predictions are extremely accurate and independently verifiable. When pink noise is applied to a system in the field, the results will track extremely closely to those predicted in MAPP. Meyer Sound Laboratories • 2832 San Pablo Ave. • Berkeley, CA, 94702 • +1.510.486.1166 • www.meyersound.com 01.083.008.01 TITLE: Headroom 01.083.008.01 Predictions Using B-­‐Noise in MAPP XT Part Introducing TITLE: Number: B - Noise Headroom Predictions Using B-­‐Noise in MAPP XT Part Introducing Number: B -Noise To help our users understand how loudspeakers react to different input signals, Meyer ToSound help hasour developedusers understand an additional how loudspeakers input source react for to differentMAPP called input B signa-Noisels,. Meyer Sound has 01.083.008.01developed an additional input source for MAPP called B-Noise. Headroom PredictionsTITLE: Using B-Noise Headroom in MAPP Predictions XT Using B-­‐Noise in MAPP XT MEYER SOUND Part Introducing Number: B -Noise “Band-Limited Pink Noise” is pink noise that has been filtered using the “Band-Limited Pink Noise” is pink noise that has been filtered using the following B-ContourTo help our formula:users understand how loudspeakers react to different input signals, Introducingfollowing B-NoiseMeyer B- SoundContour has developed formula: an additional input source for MAPP called B-Noise. “Band-Limited Pink Noise” is pink noise that has been filtered To help our users understand“Band-Limited how loudspeakers Pink Noise” is react pink noise that has been filtered using the to different input signals,following Meyer BSound-Contour has formula: developed an using the following B-Contour formula: dB BanddB- LimitedBand -Limited Pink NPinkoise N oiseat a atgiven a given frequency frequency additional input source for MAPP called B-Noise. dB Band-Limited Pink Noise at a given frequency where:where: dB Band-Limited Pink Noise at a given frequency where: where: f =f = 0. 17 0.17 + + 20 20∗∗loglog((RbRb((ff)) f = 0.17 + 20 ∗ log(Rb(f)) ! ! ! !! ! 1220012200∗ f ∗ f !! ! !! 12200! ! ∗! f ! ! !.! ! !.! Rb Rbf !f== ! ! ! ! ! !.! Giving GivingtheRb r esult:thef result:= ff + 2020.6.6 f +f12200+ 12200f + 158.5f + 158.5 Giving the result: f + 20.6 f Giving+ 12200 the result: f + 158.5 Band-Limited Pink Noise (B) 6 Band-Limited Pink Noise (B) 6 0 Band-Limited Pink Noise (B) 6 -6 0 -12 0 -6 -18 Band-Limited Pink -6 -12 -24 Noise (B) -30 -12 -18 -36 Band-Limited Pink dB 16 20 25 31 39 50 63 79 99 Noise (B) 250 315 397 500 630 -24 125 157 198 -18 794 1000 1260 1587 2000 2520 3175 4000 5040 6350 8000 Band-Limited Pink Frequency 10079 12699 16000 -24 -30 Noise (B) -36 -30 The above graph indicates that B-Noise has less spectral content in the extreme 20 25 31 39 50 63 79 99 dB 16 high frequencies and low frequencies than in the mid band. Now Meyer Sound 250 315 397 500 630 125 157 198 -36 794 users will be able to view the headroom of their1000 1260 systems1587 2000 2520 from3175 4000 5040 the6350 per8000 spective Frequency 10079 12699 16000 20 25 31 39 50 63 79 99 dB 16 of two different input signals. Here is the result of a B-Noise input: 250 315 397 500 630 125 157 198 794 1000 1260 1587 2000 2520 3175 4000 5040 6350 8000 The above graph indicates that B-Noise has lessFrequency spectral content headroom of their10079 systems12699 16000 from the perspective of two different in the extremeThe high above frequencies graph and indicates low frequencies that B -thanNoise in hasinput less signals. spectral content in the extreme the mid band.high Now frequenciesMeyer Sound users and will low be frequencies able to view the than in the mid band. Now Meyer Sound The aboveusers graph will be indicates able to view that the B- Noiseheadroom has ofless their spectral systems content from the in perthespective extreme high frequenciesof two different and lowinput frequencies signalsHere. Hereis the than resultis the inof resultathe B-Noise mid of input: a band B-Noise. Now input Meyer: Sound users will be able to view the headroom of their systems from the perspective of two different input signals. Here is the result of a B-Noise input: UPQ B-Noise at 1m: A-weighted average = 114dB, Linear Peak SPL = 134dB UPQ B-Noise at 1m: A-weighted average = 114dB, Linear Peak SPL = 134dB UPQ B-Noise at 1m: 1/3 Octave Spectrum A Weighted Average = 120 dB Z Peak = 134 dB UPQ B-Noise at 1m: A-weighted average = 114dB, Linear Peak SPL = 134dB Real-World SPL The Pink Noise and B-Noise SPL predictions in MAPP XT are B-Noise and Linear Peak SPL information in MAPP XT ensures independently verifiable, and are intended to represent linear an accurate representation of our products’ capabilities. Meyer reproduction levels of real-world signals lasting hours, as Sound makes extremely powerful loudspeakers and wishes to opposed to test bursts lasting only a few milliseconds, which represent them with specifications based on repeatable, linear, are the basis of the Max Peak SPL specification. The inclusion of real-world measurements. 2 Copyright 2015, Meyer Sound Laboratories, Inc., All rights reserved. 18.908.202.01 A.