Safeguarding test signals for acoustic measurement using arbitrary sounds (2112.11373v1)

Abstract: We propose a simple method to measure acoustic responses using any sounds by converting them suitable for measurement. This method enables us to use music pieces for measuring acoustic conditions. It is advantageous to measure such conditions without annoying test sounds to listeners. In addition, applying the underlying idea of simultaneous measurement of multiple paths provides practically valuable features. For example, it is possible to measure deviations (temporally stable, random, and time-varying) and the impulse response while reproducing slightly modified contents under target conditions. The key idea of the proposed method is to add relatively small deterministic signals that sound like noise to the original sounds. We call the converted sounds safeguarded test signals.

• The paper introduces a novel method that converts arbitrary sounds, such as music, into "safeguarded test signals" by adding deterministic noise, allowing their use for acoustic measurement instead of traditional annoying signals.
• This method utilizes periodically repetitive safeguarded signals and Discrete Fourier Transform (DFT) for impulse response calculation, with numerical simulations confirming feasibility and measurement accuracy.
• The technique enables acoustic measurement in sensitive environments like concert halls without disrupting the auditory experience and highlights potential for refined frequency-dependent safeguarding methods.

Safeguarding Test Signals for Acoustic Measurement Using Arbitrary Sounds

The paper "Safeguarding test signals for acoustic measurement using arbitrary sounds," authored by Hideki Kawahara and Kohei Yatabe, introduces a novel approach to measuring acoustic responses using music as the source signal. The authors address the common challenge in acoustic measurements that traditionally rely on synthetic test signals, which can be intrusive or unpleasant for listeners. Their method facilitates impulse response measurements without utilizing conventional annoying test sounds.

Proposed Method and Implementation

The method proposed converts any sound into a measurement-appropriate signal by adding deterministic noise-like signals to it, termed "safeguarded test signals." This approach allows the use of arbitrarily selected pieces of music to evaluate acoustic properties. The conversion retains the original characteristics of the sound while rendering it suitable for precise acoustic measurements.

A key advancement in this research is the use of periodically repetitive signals and the Discrete Fourier Transform (DFT) for computing the impulse response of the acoustic system under investigation. Because the signal remains periodic, the DFT ratios of output to input signals align closely with the system's impulse response, given the ensured non-zero condition for $X[k]$.

Numerical Results and Analysis

Extensive numerical simulations confirm the feasibility of this method. The tests involve safeguarding white noise by flooring low-level DFT values, which significantly reduces maximum deviations in impulse response estimations. Noteworthy quantitative results include an analysis showing that safeguarding does not compromise the original signal's quality; for instance, safeguarding music preserves its acoustic fidelity while ensuring high measurement accuracy.

Experiments employ different music pieces and assess aspects such as time-invariant and random responses, even under noisy conditions. The paper outlines techniques for distinguishing between linear and nonlinear responses, emphasizing how safeguarding facilitates robust measurements by mitigating sources of measurement error, such as random observation noise or signal-induced deterministic errors.

Application and Implications

The implications of this research are substantial. By allowing arbitrary sounds, such as music, to serve as test signals, this method has practical applicability in environments such as concert halls or classrooms, where maintaining an undisturbed auditory experience is critical. Moreover, safeguarding test signals opens up new avenues for acoustic assessment without introducing artificial sounds that might skew environmental acoustics or listener experience.

From a theoretical perspective, this paper casts light on spectral flooring and introduces a methodology for minimizing deviations in signal gains, contributing a new understanding of how deterministic spectral modifications can impact audio system measurements. Future research might delve into refined frequency-dependent safeguarding techniques or explore adaptive algorithms to adjust safeguarding dynamically based on the acoustic environment.

In summary, the paper presents a solid framework for leveraging arbitrary sounds in acoustic measurements, delivering both practical utility and potential for further theoretical exploration. Such advancements contribute significantly to the domain of acoustics, facilitating accurate, seamless measurement amid real-world applications.