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.

Filter by
Sorted by
Tagged with
0
votes
0answers
14 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 ...
0
votes
2answers
55 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
1answer
31 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
1answer
22 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
1answer
32 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 ...
0
votes
0answers
11 views

Linear Kernel seems to be only Kernel to predict Class from Spectral Data in Support Vector Machine

I made a Support Vector Machine in Python using the sklearn library. The data I am using is Amplitude vs Frequency for 200-520 kHz with a 0.33 kHz step. My input data is the amplitude value for my n-...
1
vote
1answer
33 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 '...
0
votes
0answers
55 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 ...
1
vote
0answers
32 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 ...
2
votes
1answer
101 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
votes
1answer
101 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
0answers
46 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
1answer
31 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
1answer
34 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
votes
1answer
24 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
1answer
50 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 ...
0
votes
1answer
103 views

What are the limitations of using Magnetic induction rather than acoustic communication in underwater communication

In underwater environment, Why acoustic underwater communications are still famous more than magnetic induction communication however in magnetic induction underwater communication, higher data rate ...
0
votes
1answer
3k views

What is the difference between undersampling and oversampling in analog to digital conversion ?

When converting a signal from analog to digital, we observe undersampling and oversampling. Does oversampling means that the sampling frequency is greater that the signal's frequency and does ...
2
votes
3answers
687 views

What is the (approximate) function for amplitude of a plucked string over time? Does it differ between string types?

Impetus: I'm currently working on my first synthesizer, after many years of playing with them. I've just added an ADSR envelope to modify the gain, but for some reason it sounds wrong to me. I've ...
8
votes
8answers
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 ...
3
votes
1answer
81 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 ...
2
votes
1answer
35 views

Why is the sound field intensity due to $K$ point sources given by $ I(p,\omega) = \sum_{k=1}^K \sigma_k^2(\omega) \delta(p - p_k)$?

I am trying to understand the following piece of text. I am not used to dealing with sound intensity and power so I'm not familiar with the derivation of the formula $(*)$ below. Statement: 1. We ...
0
votes
1answer
66 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, -...
1
vote
1answer
721 views

Explanation of OASPL and SEL

I have data of different SPL for different 1/3 center frequencies. Is it correct to sum the pressures at a mean square basis of those SPL values (and then convert them back to SPL) to obtain the OASPL ...
0
votes
1answer
299 views

How to measure acoustic pressure level under water with a hydrophone?

this is my first post here and I am also new in signal processing. Let's say I have a hydrophone with amplifier which is connected to a sound card plugged in to a computer. I gather the sounds to a ...
1
vote
3answers
296 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
1answer
63 views

Why do third-octave bands have a ratio of cube root of two?

Without sounding tautological, I guess it boils down to the definition of the third octave, which is not: 2/3*Fc but defined as the cube root of 2 ratio between frequencies. Why is a third-octave ...
0
votes
2answers
102 views

What to do for the right FFT in Matlab (two peaks and incorrect amplitude)?

This is the FFT I'm using. But two peaks (did not expect the one in the beginning) are occurring and the amplitude is not as specified (expecting a value of 2). Any help is much appreciated! ...
0
votes
1answer
261 views

Measuring acoustic phase difference between two receivers

I am trying to measure the acoustic phase difference between two sensors 30cm apart each other. The sampling frequency is 20kHz, and my interest frequency is about 1700 Hz. The below is how I ...
0
votes
1answer
90 views

Channel Shortening for underwater acoustic channel communication

I'm new in this forum, hope that we can learn from each other well. I need to ask about the channel shortening for underwater acoustic channel. what are the common algorithms in that field? is ...
3
votes
3answers
170 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 ...
0
votes
3answers
133 views

Acoustic waves propagation distance relation with carrier frequency?

In electromagnetic waves, the energy formula is $E=hf$, that means frequency increasing will increase energy and so on the propagation distance. In underwater acoustic waves, low frequencies can ...
3
votes
0answers
95 views

Energy Detection in Presence of Colored Gaussian Noise

Before asking my question, let me introduce the context: For spectrum sensing based on energy detection, which has been widely studied in presence of AWGN, the optimal detection threshold is computed ...
1
vote
1answer
182 views

sound source localization - finding source vector

This may sound a stupid question - but I am working on some simple microphone array beamforming sound source localization stuff. I think I understand how to use beamforming to find the TOA of the ...
1
vote
1answer
149 views

Can I have some feedback on this research paper?

I have submitted this paper "Effect of Transducer Positioning in Active Noise Control" to arXiv. I would like to get some feedback on the methodology of the same. Inputs of any sort are welcome. Can ...
1
vote
2answers
88 views

Digital filter simulating hydroacoustic signal distortion

Preambule: I'm designing a sound model for my small submarine game. Model is running on the server, and I want to present the client with a mono-channel wav-stream from his hydrophone (20kHz ...
4
votes
1answer
1k 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 ...
0
votes
1answer
34 views

How to model airborne sound channel

I'm making a soft demodulation/decoding to communicate a microphone and a speaker in short range. I have to calculate the LLR using my constellation and the airborne sound channel probability density ...
0
votes
0answers
40 views

Applying the inverse FFT to even out a room's sound - What is the more efficient algorithm?

I have a way (the standard way) to correct for my room's acoustics, but I'm wondering if there's a more efficient algorithm, something that doesn't involve going to the frequency domain maybe? I ...
0
votes
1answer
308 views

Is Phase Locked Loop is essential for BPSK signal reception?

I'm noob in DSP studying BPSK communication between speaker and microphone using acoustic signal. I read article of this BPSK communication which says it needs Phase Locked Loop(PLL) sequence to match ...
0
votes
2answers
994 views

What is the main difference between the acoustic and electromagnetic waves?

For simulation purpose, what will be the difference between using acoustic and electromagnetic waves? Just the carrier frequency only??
6
votes
3answers
7k views

How to change speed of audio samples without changing pitch? [duplicate]

This question may be more appropriate on music stack exchange but since sound is a branch of physics and this is more of a technical question relating to sound waves than a musical question I asked it ...
3
votes
0answers
187 views

Room Impulse Response Inverse Problem

This article here talks about a room impulse response generator which takes the source and destination coordinates, sound speed, sampling rate, room dimension and wall reflection coefficients as input ...
2
votes
1answer
236 views

Autoregressive modeling (linear prediction) of electrical transmission lines?

I've read that the reflection coefficients in speech processing (as computed by the Levinson-Durbin algorithm for solving the Yule-Walker equations) "represent the fraction of energy reflected back" ...
1
vote
2answers
2k views

Pa^2/Hz to dB/Hz conversion

I have PSD data from an computational aeroacoustics analysis, which is in the units of Pa^2/Hz. I want to convert this to dB/hz; would it be correct if I use PSD[in dB/Hz] = 10log10(PSD[in Pa^2/Hz]) ...
1
vote
1answer
16k views

dB/hz to dB Conversion

I'm have a PSD graph of dB/hz vs. frequency in hz. I want to convert the dB/hz unit to dB, but I can't find any way of doing it. Help would be much appreciated!
1
vote
1answer
123 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 ...
0
votes
1answer
390 views

What is homogeneous noise field?

What is the formal definition of homogeneous noise field? Is there any example of it? Thanks.
3
votes
2answers
440 views

Sound absorption coefficients for frequencies higher than 8kHz and lower than 80Hz?

I am building a matlab simulation that applies room compensation to a 3D audio rendering system, and I'm searching for the frequency dependent sound absorption coefficients of various materials in ...