All Questions
Tagged with signal-processing acoustics
59
questions
7
votes
5
answers
2k
views
How exactly does a seashell make the humming sound?
My little brother asked me where the ocean-like sounds came from inside of a sea shell. I told him that the air trapped inside the shell vibrates, making a sound. But then he asked me why the air had ...
- 11
-2
votes
1
answer
2k
views
Why does a running fan causes some soundproofing in the room?
I notice that when I switch on my fan inside my room, the room becomes soundproof to a great extent to the outside noises. The greater is the speed of the fan, the greater is the soundproofing.
When ...
- 207k
12
votes
8
answers
5k
views
Feynman claimed "The ear is not very sensitive to the relative phases of the harmonics." Is that true?
In The Feynman Lectures on Physics, Dr. Richard Feynman claimed that the ear (I assume he meant the human ear) is not sensitive to the relative phases of harmonics.
However, I was asked to test ...
- 348
1
vote
2
answers
6k
views
Compression vs Rarefaction in Sound Waves
I am currently looking into solutions for Sound Classification, and I came across Ludvigsen's methodology (if anyone wishes to refer to it).
The problem is that a sample graph of amplitudes in one of ...
1
vote
1
answer
54
views
How to justify sound propagation is a linear time-invariant (LTI) system?
Background
A linear time-invariant (LTI) system (black box) is one described by the system:
\begin{align}
\dot{\xi}(t) & = A\xi(t) + B\omega(t), \; \xi(0) = 0 \label{eq-abc-1}\\
\lambda(t)...
- 21.8k
1
vote
3
answers
7k
views
Do electromagnetic waves produce sound?
Preamble:
At 5 AM in the morning, if I sit quietly and listen attentively, I can hear many different noises, on a very high frequency. If I try to isolate the ones that are less noisy, I can clearly ...
- 1
0
votes
0
answers
27
views
Comparison between wave equation theory and transfer function theory
I deal with analysis of acoustic signals in solids. And after some literature research in physics and mathematic, I have a question about the followings two theories:
Wave equation theory: Imagine I ...
3
votes
1
answer
112
views
Is it possible to estimate the number of people in a room from a limited number of simultaneously recorded audio samples?
Note: I struggled to decide the appropriate site for this question, between https://physics.stackexchange.com/, https://video.stackexchange.com/, https://math.stackexchange.com/, and even https://...
- 1,785
0
votes
0
answers
21
views
FWHM and Beam Width of transmitted beam of ultrasonic (ultrasound) transducer
Im a studying ultrasonic transducer and I got a question about FWHM and Beam Width while solving some problems.
In the lecture, I learned that Beam width is calculated by:
$2\Delta\theta = \frac{3.8\...
- 207k
10
votes
6
answers
3k
views
Can sound waves be modulated?
Can you modulate sound waves? Like can you have a sound wave of a relatively low frequency and modulate it with a sound wave of a much higher frequency which people cannot hear and send it through the ...
- 7,914
0
votes
0
answers
24
views
Is the strongest acoustic signal always the closest?
I have a single beam echosounder that I use to measure the distance to an object underwater. It emits an acoustic pulse and listens to the reflections. Using the time of flight and the strongest ...
- 1
22
votes
12
answers
8k
views
How do computers store sound waves just by sampling the amplitude of a wave and not the frequency?
All of this just doesn’t make sense though.
I mean, doesn’t the amplitude represent the loudness and the frequency the pitch? Aren’t they completely independent from each other?
Is the book just ...
12
votes
3
answers
4k
views
Avoiding radar detection using active noise control instead of a stealth fuselage
was reading about different stealth technologies used by modern aircrafts to avoid radar detection.
Wouldn't it be easier to have a receiver on the airplane listening on the radar frequencies and then ...
- 49.9k
1
vote
0
answers
86
views
Modeling an Acoustic Reflection from a Wall
I am trying to simulate the reflection of a sound ray, that goes from a sound source, bounces off a wall, and is received by a microphone.
The wall has a an absorption coefficient, and a specular ...
- 11
0
votes
1
answer
145
views
What is the physical meaning of the pressure of an acoustic point source being complex?
Context
From various sources of Acoustics (such as "Acoustics -
An Introduction to Its Physical Principles and Applications" by Allan D. Pierce and "Fundamentals of General Linear ...
- 13.1k