Questions tagged [acoustics]

Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. Applications of acoustics are for instance the audio and noise control industries.

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1 answer
136 views

MUSIC implementation in Pyroomacoustics library

I am currently using the multiple signal classification (MUSIC) algorithm provided by the Pyroomacoustics library in order to estimate direction of arrival angles and it works pretty well for both ...
8 votes
2 answers
17k views

Calculation of Reverberation Time (RT60) from the Impulse Response

I have some confusions regarding reverberation time (RT60). I need to calculate reverberation time from a given power envelope. This is what I get. As you might see the line is curved close to zero (...
2 votes
2 answers
534 views

GCC-PHAT for Multiple Sound Sources

Can GCC-PHAT be used to detect multiple time-delays (that is, having multiple acoustic sources simultaneously)? The documentation for the gccphat(sig,refsig) ...
1 vote
0 answers
64 views

Meaning of "standard deviation noises of wavelet coefficients"

I am currently working on a research project based on the paper titled A deep learning approach for anomaly detection based on SAE and LSTM in mechanical equipment. The paper uses data in the acoustic ...
1 vote
1 answer
292 views

Comparing spectrogram similarity over time

I have a data set of spectrograms from moving audio recorders. As the recorders get closer, I expect the spectrograms to become more "similar". I expect this "similarity" to be a ...
1 vote
0 answers
32 views

Realtime classification of (one of 12) vowel phonemes

I'm attempting realtime classification of (one of 12) vowel phonemes, sung (steady-state-ish) into a microphone. MOTIVATION: Suppose my user sings a MIDI note using a steady-state vowel phoneme (no ...
-1 votes
1 answer
55 views

Filter model of passive attenuation of headphones

It is possible to model passive attenuation of headphones as a Matlab/Python filter ? For example I would like to find digital filter which will be simulating the way of the passive attentuation of ...
8 votes
1 answer
184 views

MUSIC Algorithm for Direction of Arrival (DOA) in Acoustic Signals

I have seen multiple reviews of the MUSIC algorithm for the estimation of DOA. Most of those reviews consider a complex signal input with a complex steering vector. So, how do I implement this ...
2 votes
1 answer
219 views

How to convert multi-band Energy Time Curve (ETC) to Impulse Response (IR)?

I am running my own sound simulator. Now I have obtained the Energy Time Curve (ETC, expressed by energy) by physical simulation, and they are stored in 8 discrete frequency bands (because decay of ...
1 vote
1 answer
34 views

Simulated Room Transfer Function

I need help obtaining a simulated transfer function in a simulated room. I have created image sources for first and second order reflections, and am assuming a point source for my source. I have the ...
2 votes
2 answers
118 views

2D Spatial Fourier Tranform on a pressure field

I'm doing some research on Fourier Near-field Acoustic Holography (NAH). The basic theory behind Fouerir NAH is that you take a sound pressure field measurement in a 2d plane p(x,y), 2d spatial ...
1 vote
1 answer
115 views

Calculation of Reverberation Time (RT60) by interrupted noise method

As part of my thesis,I want to write in Delphi the algorithm to calculate the reverberation time using interrupted noise method. Delphi, Signal processing and accoustics are new topics for me. Room ...
1 vote
1 answer
36 views

How to normalise 3D time-frequency sound intensity vector

I've got a 3D time-frequency sound intensity vector that I've derived from Ambisonic b-format signals. W acts as the sound pressure ...
0 votes
0 answers
53 views

RT 60 from Impulse response

I have already the impulse response of an acoustic environment in the form of a series of signals over 300 samples. I have tried the procedure given in this platform - i.e. low pass filtering, Hilbert ...
0 votes
0 answers
48 views

Calculation of ITD (Interaural time delay) using linear prediction - python

How is it possible to calculate the interaural time delay between two signals recorded underwater (ship sound signals)? Will linear prediction weight method be used for this?
1 vote
2 answers
37 views

A way to estimate beat frequency from two audio sources

I am accordion repairer and also an engineer. I plan to make a useful tool in Python to help with tuning. In an accordion, there are several reeds making different sounds at different frequencies, and ...
1 vote
1 answer
58 views

Estimating reverberant time (T60) of an IIR filter

I'm learning a method to genenrate pink noise by filtering a white noise in this book, and the author mentioned an estimation of T60 given the coefficients of an IIR filter in the code that ...
1 vote
1 answer
29 views

How to apply an atmospheric attenuation filter in the freq domain and then convert the filtered signal back to the time domain?

This question is a part of a more general question the answer of which I don't know - How to apply a filter in the freq domain and then convert the filtered signal back to the time domain? Well, I ...
0 votes
1 answer
26 views

Indian Space Research Organization - Extent of spectral spread 1/3rd Octave Analysis [closed]

I am a scientist at Indian Space Research Organization (ISRO) and will be representing my team. We work on Telemetry and Data Handling units for our Launch Vehicles. We are preparing for our upcoming ...
0 votes
1 answer
113 views

RMS level from impulse response

I am trying to quantify the average differences between several impulse responses over the frequency range and over octave bands. So, I am doing (in Matlab): ...
0 votes
1 answer
89 views

sound source localization - calculation of sound intensity vector angles

I'm working on an acoustic source separation problem where I want to separate the voices of a choir based on intensity vector statistics. I'm currently implementing a paper by Günel called “Acoustic ...
9 votes
8 answers
3k views

Is sound the best way to transmit a signal under water?

Could sound be used in transmitting sound waves under water digitally? Could the sound then be converted by a repeater to transit by radio waves? What other ways can a signal be transmitted other than ...
0 votes
1 answer
102 views

Hydrophone kit to transmit (and receive) underwater

May I ask you if there exists a complete kit (e.g., by including the amplifier, etc.) of professional hydrophones to transmit and receive signals in underwater environments? If not, can I ask you for ...
1 vote
1 answer
66 views

Echo Removal from PCM 16 bit arrays (time frames)?

I am keen to know the basics to remove echo knowing FarEnd Signal and NearEnd Signal. I have read research papers in which its commonly said: y(n) = (hT)x where h is the room impulse response and T ...
2 votes
1 answer
111 views

Why use complex envelope to model raw measurements?

The usual answers when asking "why use complex numbers to model measurements?" is usually: (a) Because you are measuring a phenomenon like electricity and magnetism. (b) Because it is super ...
1 vote
2 answers
177 views

Should I pass Kalman Filter absolute or offset-from-mean sensor values?

I'm using Kalman filters to segment the loudness of an acoustic signal from surrounding noise. The problem I've encountered is that muffled or faulty microphones measuring 'silence' (-70dB, -69dB, -...
0 votes
1 answer
31 views

Multiple short-range impulse responses aggregated to simulate a long-distance impulse response

I'm a biologist and I was thinking of ways that impulse responses could be used to simulate how an animal sounds over various distances in different types of forests. Ultimately, if a tool was ...
0 votes
0 answers
19 views

Estimate IR's from single channel speech audio

I have a dataset of single-channel audios containing speech, recorded in a single room. I need to extract the room IR's. The goal is to simulate the room acoustics and adjust new speech audios ...
2 votes
1 answer
42 views

Modes and wavetypes

I am studying results from vibration signals on rotating machinery, using two accelerometers. I am interested in dispersion characteristics. I have read that it is possible to identify acoustic '...
4 votes
1 answer
86 views

Artefacts from playing ultrasound through PA system

I encode data in audio by energising 5 frequencies between 17.5kHz and 19.5kHz: I play the ...
0 votes
2 answers
81 views

What do troughs represent in a sound wave?

What's the notion of negative amplitude? I hope the title and the question don't mean different things.
0 votes
1 answer
191 views

What is the driving Voltage?

While I was looking into ultrasonic transducer in order to transmit and receive a beam, I came across specification of a transducer stating driving voltage as 20Vrms. I am not sure what actually does ...
0 votes
1 answer
33 views

Statistics to characterize time-domain envelope of acoustic signal

I am interested in comparing 0.5-second 44100/s signals when different ADSR envelopes are applied to them. However, I don't want the comparison to be as fine-grained as simply calculating a 5000-...
0 votes
1 answer
59 views

How to Tx CDMA signal physically using an existing point-to-point modem? [closed]

I am working in acoustic communication, I want to test CDMA network capabilities in acoustic environment. I had an acoustic modem that has serial interface, a WHOI micromodem. How can i serialized ...
4 votes
1 answer
3k views

Calculating SPL from pressure signal - Amplitude vs Power method

I have a pressure signal from a Fluent FFowcs-Williams Hawkings acoustics analysis. I converted this pressure signal into the frequency domain in order to get SPL values, using Matlab. I used the ...
3 votes
3 answers
241 views

Is it possible to "equalise" a signal by deconvolving the impulse response of the room in which it is to be played?

I am using a test sweep with a flat power spectrum and linear group delay (Optimized Aoshima's Time Stretched Pulse) to measure a room's frequency response. Having obtained the impulse response of the ...
2 votes
3 answers
6k views

Convolving Room Impulse Response with a Wav File (python)

I have written the following code which is supposed to put echo over an available sound file. Unfortunately the output is a very noisy result which I don't exactly understand. Can anybody help me with ...
10 votes
1 answer
746 views

What are thoughts on best modulation to use for underwater acoustic communications at low frequencies?

I wanted to ping the DSP hivemind for general thoughts on what would be the best modulation type to use for low frequency underwater communications. I have chosen this project since I can learn a lot ...
-1 votes
1 answer
159 views

Doppler effect in underwater acoustic channel

I got my BER vs SNR graph as shown. I was trying to show the difference in BER with OFDM signal transmission under Doppler effect and without Doppler effect. However, based on my understanding, the ...
1 vote
3 answers
603 views

How to calibrate a signal with respect to frequency

I have recordings from accelerometers (non-flat response with respect to frequency) and I'd like to convert my voltage time series into acceleration values. Is there a standard method for doing this? ...
0 votes
0 answers
56 views

What cause frequency change of the acoustic signal (3 kHz to 10 kHz)?

I am working on Acoustic Resonace testing in which I excite the sample and then record the sound (3 kHz to 10 kHz) by microphones. I do few times repetation of the same measurement in series (one ...
6 votes
2 answers
3k views

What are reasonable levels for the ERLE (Echo Return Loss Enhancement) in acoustic echo cancellation?

I am working on acoustic echo cancellation which has a double talk detector. During the single talk, the ERLE (Echo Return Loss Enhancement) exceeds 100dB and during double talk around 20dB to 40 dB. ...
1 vote
0 answers
51 views

Is fundamental frequency information present in speech-shaped white noise?

I am using a so-called speech-shaped stationary white noise, which means so much as a white noise that has been filtered to match the long-term spectrum of a female speaker. The way it was generated ...
0 votes
0 answers
23 views

Underwater Acoustic channel simulation issue.Figure 3 Result of paper in comment are not matching. I don't know wy the values are comming half in dB [duplicate]

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1 vote
0 answers
62 views

Underwater acoustic channel is giving me a flat BER vs SNR curve

I need to do OFDM and GFDM signal transmission in underwater acoustic channel. I have my underwater acoustic channel as follow. ...
1 vote
1 answer
84 views

relationship of frequency with range in Underwater acoustic channel

I am interested to know what range of frequencies can be used/ or are effective for wireless communication, within the underwater acoustic channel. I do know a table exists from \cite{...
-1 votes
1 answer
42 views

Simulating polar pattern for custom radiator (custom speaker design)

I'm interested in performing a speaker simulation to extract an approximate polar pattern for two custom speaker designs. First design: A half wave pipe (transmission line) subwoofer 24 hz to 56 hz ...
1 vote
2 answers
118 views

Separate static echos from acoustic signal (ICA?)

I am using acoustic waves to measure the thickness of material. My problem is that the acoustical lens produces static echos in the signal. I try to separate both because there is a short interference ...
-1 votes
1 answer
28 views

How can acoustic pressure in air be measured when targeted specifically?

How can acoustic pressure in air be measured when it is targeted very specifically, e.g. at a specific person in a room or house?
0 votes
1 answer
66 views

Generating audio clip by superposing two files

I'm currently trying to generate a set of audio files where some audio events (e.g. dog bark) are immersed in a background audio scene (e.g. crowd noise). I understand that if the event would have ...