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Feedback Comments on Sound

by Ron Kurtus

A total of 189 comments and questions have been sent in. They are listed according to date.

List of most recent 10 letters




Sound and Obstacles Sound reflecting off barriers Australia
Sound Waves Can't find sound waves quiz USA
Sound and Obstacles Does density of fabric reduce echoes? Saudi Arabia
Sound Detection Upstairs neighbor making noise on the floor USA
Noise Cancellation Cancelling low frequency whispers USA
Sound and Obstacles Factory causing noise to home USA
Sound and Obstacles Someone yelling at 70 db USA
Sound Frequencies and Wavelengths Neighbor is transmitting high frequency sounds USA
Sound Waves I love to study sound USA
Sound Detection Professional specializing in sound USA

Next 10


Sound reflecting off barriers

Topic: Sound and Obstacles


March 1, 2016

Hi, my questions are as follws:

1. What barriers does sound reflect off?

2. Why does sound reflect off barriers?

3. Is the surface that the wave reflects off affecting the length off the wave?

Thank you for your time!

Sophie - Australia



Sound will reflect off any solid barrier, although some sound may be transmitted through the barrier and some may be absorbed. Sound can also be reflected off a "barrier" of a liquid or even some gas.

Sound is a series of compression waves where molecules move a short distance, causing the next group to move. If there is a barrier, the wave of molecules would bounce off in the other direction.

The only time the length of the wave (wavelength) changes on reflection is if the barrier is moving, causing the Doppler Effect.

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Can't find sound waves quiz

Topic: Sound Waves


February 25, 2016

i cant find the quiz anywhere plz help seriously




You can click on the Mini-Quiz tab at near the top of the page for a short quiz on the subject. Also, there is a larger Graded Physics Test on Sound Waves that you can access.

I hope that helps.

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Does density of fabric reduce echoes?

Topic: Sound and Obstacles


February 15, 2016


Moh'd Jamal - Saudi Arabia



Heavy drapes over a window helps to reduce outside sound much better than thin curtains. Now to reduce an echo, many concert halls used to use a heavy fabric on the walls to absorb the sound. However, these days most use sound absorbing wall and ceiling materials. But I don't think they do as good of a job.

You don't want the fabric to be so dense that it is almost hard. Then it would actually do little to reduce the echo. You want the sound to travel into the spaces in the fabric and then get absorbed.

I hope that helps.

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Upstairs neighbor making noise on the floor

Topic: Sound Detection


January 29, 2016

I am looking for something that picks up sounds say through a ceiling. I have a very noisy neighbor and they drag furniture and drop things hard on the floor etc and I want to either record this or have it show on some sort of graph etc or both. Can you advise me on what type of device is the best for doing this? If so and know a link ,please send it to me. Anything will be greatly appreciated. I will use this to show the police,land lord and hosing authority on what is going on day after day after day.... Any info will help. Thank you.


Lorenz - USA



It can be very annoying when the neighbor above your place makes noises on the floor. I've had the same experience.

The police do not care to get involved, since the people aren't breaking any laws.

A good thing to do is to talk to the people upstairs and politely ask them to try to make less noise on the floor. They might then be more careful. If that doesn't work, you could talk to the landlord, but that may not do much good.

Recording the noise can be done with any digital recorder or tape recorder, but I think most people would take your word for the fact that it is annoying or bothersome.

Best wishes in solving your problem. In my case, I was glad when the people moved away.

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Cancelling low frequency whispers

Topic: Noise Cancellation


January 24, 2016

How can someone cancel human speech, especially low frequency and low pitch whispers? Since spoken sounds contain many different wavelengths and frequencies it, in theory, should be easier to match a whisper with a 180 degree amplitude my thinking correct? Is there anyway to interfere with /cancel the 'sound' by altering electric or magnetic fields and what kinds of equipment could /would one use? Am I wrong thinking that speech can be manipulated(I.e. broadcast ) to travel long distance via radio waves within electromagnetic field? If so, would one alter near or far field and how? Please understand: I am exploring possible alternative solutions for me a more than one application/problem. Thanks

Justin - USA



If a microphone can record low frequency and low pitch whispers, those frequencies can be cancelled out. The electronics can filter the complex waveform into distinct frequencies and amplitudes. Of course, it isn't exact, but changing the phase of the the narrow frequency bands is enough to cancel much of the sound.

Whether the sound is loud or soft doesn't affect the cancellation.

The active noise cancellation electronics uses changing electric fields to cancel the signals. You can now buy an inexpensive set of noise cancelling earphones to examine and use the electronics.

Radio waves are electromagnetic waves within the radio frequency band.

Best wishes in creating alternative solutions.

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Factory causing noise to home

Topic: Sound and Obstacles


December 8, 2015

I live in a subdivison in town and there is a large manufacturing plant behind us. The company will not build a wall to cut down on the noise and we are left wondering what to do about it? Any ideas or suggestions would be helpful. HayneBrands, Inc, factory on Clark Rd in Clarksville, AR 72830.

Steve - USA



I am sure that living near a noisy manufacturing plant is annoying and unfortunate.

One thing you can do is to gather your neighbors and bring this problem up to your city officials. They might be able to put some heat on the company to be considerate of their neighbors.

Another possible solution is planting high shrubs or such to try to block out some of the sound. However, that might not give much relief.

Best wishes in finding a solution to your problem.

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Someone yelling at 70 db

Topic: Sound and Obstacles


November 22, 2015

If someone yelled something at 70 dcb's how much sound will make it through if the house is 100 ft away and to the left of where someone is speaking?

Phillip - USA



Yelling or very loud talking can create of sound of 70 decibels (db). Under normal conditions, the sound spreads out and decreases with the square of the distance. The sound would decrease even more if you heard it inside a house (unless the windows were open). How much also depends on the structure and insulation of the house.

However, people tend to focus on annoying sounds, making them seem more noticeable and louder than they actually are.

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Neighbor is transmitting high frequency sounds

Topic: Sound Frequencies and Wavelengths


November 17, 2015

Please see the phasor painfield generator at or information unlimited. The neighbor below is using to harass me-high frequencies. How can I prove this.





I once had a neighbor who was using a high powered CB band radio that would cause my loudspeakers to transmit his loud conversations, day and night. I mentioned it to him in a friendly manner, and he then toned it down.

What I'm saying is that it might be good to approach your neighbor and ask if he knows anything about some high frequency sounds in the area. Don't accuse, but ask for information and perhaps some help. If you act nice, often people will stop what they are doing.

However, if your neighbor is a complete jerk and is really trying to harass you, at the very least, by talking to him, you can get an idea of what he is doing and why.

If it really seems to be a case of harassment with these sounds, you can then talk to your apartment manager about the situation.

But the first action is to be nice to try to get to the bottom of the issue.

I hope that helps such that the problem will be solved.

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I love to study sound

Topic: Sound Waves


October 12, 2015

i love sound.

eve - USA



I am glad you love the subject. It is very interesting and useful.

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Professional specializing in sound

Topic: Sound Detection


August 2, 2015

Is there a profession that specializes in sound. My interests are:
Identifying frequency and pitch
Measuring vibrations caused by sound
Locating orgin point

Thanks for your site, I found it informative. Im hope you know of an accredited title in the very least.

Tracy - USA



Acoustics and Acoustical Engineering are areas specializing in sound. See Acoustics and You for information about a career in Acoustics.

Also see Acoustic Engineer - Job Description and Career Requirements.

I hope that helps.

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