ArticlePDF Available

Application of calculating the reverberation time from room impulse responses without using regression

Authors:
Csaba Huszty at Entel Engineering Research & Consulting Ltd.
Csaba Huszty
  • Entel Engineering Research & Consulting Ltd.
Shinichi Sakamoto at The University of Tokyo
Shinichi Sakamoto
Download full-text PDF
Read full-text
Download citation

Abstract

This paper presents the application and a method that calculates the reverberation time based on Lp-norms. generalized measures of the room impulse response (RIR). without using regression on decay curves. The reverberation time in this approach is a function of a parameter, and is constant only in a perfectly diffuse space; therefore the method may present useful information beyond the decay time itself. Properties of this method using theoretical and real-life RIRs are examined in cases of wide-band and sub-octave-band calculations. Correction methods for the finite support of the R IR . as well as for the effects of stationary background noise are presented and the connection to previous methods is shown.
Content uploaded by Csaba Huszty
Author content
All content in this area was uploaded by Csaba Huszty on Feb 01, 2016
Content may be subject to copyright.
Application of calculating the reverberation time
from room impulse responses without using
regression
L2L2
Huszty, Sakamoto: Calculating the reverberation time without using regressionFORUM ACUSTICUM 2011
27. June - 1. July, Aalborg
60
p
p
p
p
h(t)i
n(t)i
e(t)
R k = 3 ln(10)
e(t)=exp
−kt
R
h(t)i=n(t)i·e(t)
e(t)
R
a
h(t)nd = lim
a→0
1
a√πexp −(t−R)2
a2=
=δa(t−R)
Lp
h(t, p).
=|h(t)|p
0<p≤1
p
Lp
R(p)=kp ·∞
0t·h(t, p)dt
∞
0h(t, p)dt
kp p
e(t)
h(t)p
p
ˆ
R
p
Huszty, Sakamoto: Calculating the reverberation time without using regressionFORUM ACUSTICUM 2011
27. June - 1. July, Aalborg
p
e(t)
ˆ
R=kp ·∞
0t·
exp −kt
R
pdt
∞
0
exp −kt
R
pdt =R
p
ˆ
R(p) = lim
a→0kp ·R+ak√p
√πexp (ξ2)(erf (ξ)+1)=
=kp ·R
ξ=R√p
a
ξ
p
p
L
ˆ
RL(p)=R−Lkp
exp Lkp
R−1
R
ˆ
R(p)i+1 =ˆ
RL(p)0+Lkp
exp Lkp
ˆ
R(p)i−1
ˆ
RL(p)0=kp ·L
0t·|h(t)|pdt
L
0|h(t)|pdt
i
R(p)
1%
R
L=15
1
15
N=10
5
R/L
L2
p=1
h(t) = exp −k·t
R+N
N
ˆ
R=k·
L2N
2+R2
k2−R(R+Lk)
k2exp Lk
R
LN −
R1
exp Lk
R
−1
k
Huszty, Sakamoto: Calculating the reverberation time without using regressionFORUM ACUSTICUM 2011
27. June - 1. July, Aalborg
ˆ
R=R
L=
RW02 exp(−2)
N+2
k
W0
N
p
L
p
p
00.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
Mixing
Reverberation time
T20
T30
T40
T60
New
00.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
Mixing
Reverberation time
T20
T30
T40
T60
New
R1=0.2R2=0.8
0 1 1
48000
40
p=0.55
1/3
1
Huszty, Sakamoto: Calculating the reverberation time without using regressionFORUM ACUSTICUM 2011
27. June - 1. July, Aalborg
0 0.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
Mixing
Reverberation time
T20 Noise
T20
New Noise
New
0 0.2 0.4 0.6 0.8 1
0
0.2
0.4
0.6
0.8
1
Mixing
Reverberation time
Without noise (p range)
With noise (p range)
Without noise (p=0.55)
With noise (p=0.55)
p
p
0.1 0.1 1
1 10
T30
31 62 125 250 500 1k 2k 4k 8k 16k
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
Center frequencies [Hz]
Reverberation time
Trad. Butterw.
Trad. Wavelet
New Butterw.
New Wavelet
31 62 125 250 500 1k 2k 4k 8k 16k
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
Center frequencies [Hz]
Reverberation time
Trad. CQT
New CQT
31 62 125 250 500 1k 2k 4k 8k 16k
0.99
1
1.01
1.02
1.03
1.04
1.05
Center frequencies [Hz]
Reverberation time
Trad.
New
1/3
R
p
Huszty, Sakamoto: Calculating the reverberation time without using regressionFORUM ACUSTICUM 2011
27. June - 1. July, Aalborg
00.5 11.5 2
0.8
0.8125
0.825
0.8375
0.85
0.8625
0.875
0.8875
0.9
0.9125
0.925
0.9375
0.95
0.9625
0.975
0.9875
11
p
Correlation
0 2 4 6 8 10
0
2
4
6
8
10
R [s] @ p = 0.5
T30 [s]
0 2 4 6 8 10
0
2
4
6
8
10
R [s] @ p = 1
T30 [s]
T30
p
... The author previously proposed a method to calculate the reveberation time without using regression or backward integration based on moments of the RIR and forward integration 13 . By using a smoothed representation of the RIR h(t, p) . ...
Performance comparison of monoexponential and multiexponential decay function estimation methods
Conference Paper
Full-text available
  • Sep 2013
Various decay function and decay time estimation methods show different performance properties in terms of accuracy, reliability, convenience in use and ease of implementation. In this paper a systematic way for evaluating and comparing decay function estimation methods is presented. The method is based on decay models. Commonly used monoexponential a multiexponential decay time estimation methods are compared and a new multi-component non-linear method for multiexponential decay function estimation is briefly introduced and compared to the Bayesian method. Model functions are used to evaluate the current and newly introduced methods.
View
... where is the constant as introduced in Eq. (3). Results are shown in Fig. 4a and 4b, and some more details are discussed in [4]. Note that some small EDT values are caused by a strong direct sound that affects the traditional calculation. ...
On the prediction of room acoustic parameters using a single measure
Conference Paper
Full-text available
  • Sep 2011
In this paper a generalized measure in the form of a function for a given room impulse response (RIR) is presented and examined with the goal to predict or approximate established room acoustic parameters. Theoretical assumptions for a diffuse space as well as a measurement database are used to formulate and verify the prediction methods. The correlation of the generalized measure and the established room acoustic parameters, particularly the reverberation time, the EDT and the objective clarity and definition is shown. Examples on the behavior of the general measure are presented and the additional information obtained by this general measure is also discussed.
View
... Random white noise with different levels wasa dded to a real measured impulse responses to simulate different signal to noise ratios. There are also alternative ways to calculate the reverberation time [12,13,14] that use nonlinear regression methods. However, these methods are rarely used and therefore not investigated in this study.I nt his study fiveestablished and commonly used noise compensation methods are selected and their performances are compared. ...
Comparison of Noise Compensation Methods for Room Acoustic Impulse Response Evaluations
Article
  • Mar 2014
  • ACTA ACUST UNITED AC
Noise that is part of the measured impulse responses is inevitable but can have a large impact on the evaluation of room acoustic parameters. Five well-known and widely used noise compensation methods are discussed and their performances are compared in this study. Two evaluation approaches are used to test the different methods: A simple parametric model to simulate the envelope of an impulse response including measurement noise, and in a second approach, special designed long-term measurements. These were conducted to be able to evaluate the errors as a function of the noise level. The results that are obtained using the model and the measurement approach are consistent with each other. When these methods are used to suppress noise effects, their performances differ significantly. This is also true for the three methods that are compliant with ISO 3382. Four methods cause systematic errors depending on the peak-signal to noise ratio. The reverberation time is more sensitive to noise than energy parameters such as clarity or definition. A comparison of the different excitation signals that are used for the measurement approach shows that there is no difference with regard to sine sweeps and maximum length sequences, if no impulsive noise or nonlinearities occur.
View
Automated estimation of the truncation of room impulse response by applying a nonlinear decay model
Article
  • Mar 2016
Noise represents one of the most significant disturbances in measured room impulse responses (RIRs), and it has a potentially large impact on evaluation of the decay parameters. In order to reduce noise effects, various methods have been applied, including truncation of an RIR. In this paper, a procedure for the response truncation based on a model of RIR (nonlinear decay model) is presented. The model is represented by an exponential decay plus stationary noise. Unknown parameters of the model are calculated by an optimization that minimizes the difference between the curve generated by the model and the target one of the response to be truncated. Different curves can be applied in the optimization—absolute value of the RIR, logarithmic decay curve, and Schroeder curve obtained by the backward integration of the RIR. The proposed procedure is tested on various synthesized and measured impulse responses. It is compared with the procedure taken from the literature, often applied in practice.
View
"An efficient algorithm for the calculation of a constant Q transform"
Article
Full-text available
  • Nov 1992
  • J ACOUST SOC AM
An efficient method of transforming a discrete Fourier transform (DFT) into a constant Q transform, where Q is the ratio of center frequency to bandwidth, has been devised. This method involves the calculation of kernels that are then applied to each subsequent DFT. Only a few multiples are involved in the calculation of each component of the constant Q transform, so this transformation adds a small amount to the computation. In effect, this method makes it possible to take full advantage of the computational efficiency of the fast Fourier transform (FFT). Graphical examples of the application of this calculation to musical signals are given for sounds produced by a clarinet and a violin.
View
An Objective Criterion for the Measurement of Echo Disturbances during Presentation of Music and Speech.
Article
  • May 1986
The cause of echo-disturbances during presentation of music and speech in rooms has been investigated in a synthetic sound field. Arising out of the echo analysis a new method is proposed for analysing impulse responses in rooms. In numerous additional tests the new method was verified by comparing subjective judgements on echo disturbances with the respective impulse response, in the synthetic sound field as well as in real rooms.
View
Environmental and Architectural Acoustics
Book
  • Jan 2011
The revised new edition of a classic guide adopts a multi-disciplinary approach to the challenge of creating an acceptable acoustic environment. It draws on the same basic principles to cover both outdoor and indoor space. Starting with the fundamentals of sound waves and hearing, it goes on to the measurement of noise and vibration, room acoustics, sound absorption, airborne sound insulation and noise and vibration control. Each chapter finishes with useful problem-solving exercises to assist comprehension. The strong focus on techniques, methods and standards, and with its lead into further more specialised material, makes this book highly useful for advanced students and professional engineers. The new updated coverage of international standards makes this book even more useful. It also serves as a foundation reference for students of architecture and environmental engineering, including those new to the study of acoustics.
View
Estimation of modal decay parameters from noisy response measurements
Article
  • Nov 2002
  • J AUDIO ENG SOC
The estimation of modal decay parameters from noisy measurements of reverberant and resonating systems is a common problem in audio and acoustics, such as in room and concert hall measurements or musical instrument modeling. Reliable methods to estimate the initial response level, decay rate, and noise floor level from noisy measurement data are studied and compared. A new method, based on the nonlinear optimization of a model for exponential decay plus stationary noise floor, is presented. A comparison with traditional decay parameter estimation techniques using simulated measurement data shows that the proposed method outperforms in accuracy and robustness, especially in extreme SNR conditions. Three cases of practical applications of the method are demonstrated.
View
View
View
Ein objektives Kriterium zur Erfassung von Echostörungen bei Musik- und Sprachdarbietungen
Article
  • Jan 1986
  • ACTA ACUST UNITED AC
The cause of echo-disturbances during presentation of music and speech in rooms has been investigated in a synthetic sound field. Arising out of the echo analysis a new method is proposed for analysing impulse responses in rooms. In numerous additional tests the new method was verified by comparing subjective judgements on echo disturbances with the respective impulse response, in the synthetic sound field as well as in real rooms.Zusammenfassung Durch subjektive Tests in einem synthetischen Schallfeld wurde das Zustandekommen von Echostörungen bei Musik und Sprache untersucht. In Auswertung der Meßergebnisse wird ein neues Echoanalyseverfahren für die Anwendung beim raumakustischen Impulsschalltest vorgeschlagen. Das Echoanalyseverfahren wurde durch zusätzliche umfangreiche Tests im synthetischen Schallfeld sowie durch Auswertung von subjektiven Urteilen und Raumimpulsantworten in realen Zuhörerräumen überprüft und bestätigt.Sommaire On avait commencé par rechercher les manifestations d'une gêne due aux échos, au cours de la présentation de musique ou de parole dans une salle, au moyen de tests subjectifs en champ acoustique synthétique. L'examen des résultats a suggéré un nouveau procédé d'analyse des échos reposant sur l'étude de la réponse impulsionnelle de la salle et permettant de sélectionner les échos gênants. La validité de cette nouvelle méthode a été vérifiée par de nombreuses expériences, en champ réel comme en champ synthétique, avec comparaison entre des réponses impulsionnelles et des jugements subjectifs.
View
Concert Halls and Opera Houses: Music, Acoustics, and Architecture (Second Edition)
Article
  • Mar 2005
The Journal of the Acoustical Society of America 117(3), 987 (2005) DOI: http://doi.org/10.1121/1.1861061
View
Uncertainties of Measurements in Room Acoustics
Article
  • Jul 1995
  • ACTA ACUST UNITED AC
The influence of several sources of error on room acoustical measurements have been investigated using maximum-length sequences (MLS). The algorithms for the determination of room acoustical parameters used by different analyzers introduce systematic differences caused by differences in time windowing and filtering, in reverse-time integration and in noise compensation. The overall uncertainty of measurements is of the same magnitude or a little higher than subjectively perceivable changes in room acoustical parameters when the measurements are performed according to ISO/DIS 3382. However, the draft standard allows various procedures to be applied in the processing of impulse responses.
View
Calculation of a Constant Q Spectral Transform
Article
  • Jan 1991
The frequencies that have been chosen to make up the scale of Western music are geometrically spaced. Thus the discrete Fourier transform (DFT), although extremely efficient in the fast Fourier transform implementation, yields components which do not map efficiently to musical frequencies. This is because the frequency components calculated with the DFT are separated by a constant frequency difference and with a constant resolution. A calculation similar to a discrete Fourier transform but with a constant ratio of center frequency to resolution has been made; this is a constant Q transform and is equivalent to a 1/24-oct filter bank. Thus there are two frequency components for each musical note so that two adjacent notes in the musical scale played simultaneously can be resolved anywhere in the musical frequency range. This transform against log (frequency) to obtain a constant pattern in the frequency domain for sounds with harmonic frequency components has been plotted. This is compared to the conventional DFT that yields a constant spacing between frequency components. In addition to advantages for resolution, representation with a constant pattern has the advantage that note identification ("note identification" rather than the term "pitch tracking," which is widely used in the signal processing community, is being used since the editor has correctly pointed out that "pitch" should be reserved for a perceptual contest), instrument recognition, and signal separation can be done elegantly by a straightforward pattern recognition algorithm.
View