# 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 next 10 letters

### Country

Sound Waves Relating numerology of names and sounds UK

Sound from a Wire Equation Changing the thickness of a wire changes sound USA

Noise Cancellation Bothered by noisy water heater USA

Sound Frequencies and Wavelengths Ultrasound and AM radio UK

Sound from a String Equation Solving frequencies for a wire Philippines

Sound from a Wire Equation Numbers are switched Netherlands

Sound and Obstacles Can sound cause a material to lose its strength? India

Noise Cancellation Noise cancelling microphones for ships UK

Sound Beats Beats don't work for me USA

Noise Cancellation Stopping furnace extractor fan noise Canada

Next 10

First 10 letters

## Relating numerology of names and sounds

Topic: Sound Waves

### Question

November 11, 2012

Hello,

I'm a student of numerology and am very interested in sound and the way a name is said. I can work out names which equal the same number but would have different vibrations.

For example.
Guy - 14 = 5
Molly - 86 = 14 = 5
John - 59 = 14 = 5

As you can see they are different names and vibrations, what i want to know is would the names share any characteristics that would give away their number if i didn't know the number of the names.

-- Thanks

Ian - UK

23031

The method in numerology is to assign the letters in a name numbers according to the rank of the letters, such as A = 1, B = 2, etc.

However, if you try to relate the number to sound, you really don't get a correspondence. Guy and John may have the same end number, but they are pronounced differently and thus have a different set of wavelengths. Also, Guy is pronounced differently in France than it is in the UK.

Molly consists of two syllables: Moll and -y. Its sound would be much different than a name with one syllable.

At the very least, it is an interesting area to look into.

## Changing the thickness of a wire changes sound

Topic: Sound from a Wire Equation

### Question

November 10, 2012

Does the sound change if the thickness of the wire changes?

zuzu - USA

23030

The equation for the frequency is: f = (1/Ld)*(T/À´)where d is the diameter or thickness of the wire.

That means that when the thickness increases, the frequency of the sound decreases and it pitch goes down. If you make the wire thinner, the frequency goes up.

## Bothered by noisy water heater

Topic: Noise Cancellation

### Question

October 14, 2012

You can measure the noise then create a canceling noise. Where to get such equipment?
The water heater in an apartment is creating a noise (vibration) from the electric moters.
How could we reduce the level?

Mic - USA

22984

Although there are some sophisticated equipment that will cancel out equipment noise, the only practical way yo cancel noise is through noise-cancelling earphones.

Instead, you can try to reduce the noise. See Noise Reduction of Sound for information.

Since the problem is in your apartment, you should talk to the apartment manager about trying to fix the problem. Sound proofing in the water heater area and around the electric motors could help a lot.

Best wishes in solving your noise problem.

## Ultrasound and AM radio

Topic: Sound Frequencies and Wavelengths

### Question

October 2, 2012

I found this page most interesting and pretty useful but there is one question I am struggling to get answered online and wonder if you could help.

I'm looking to study and test record in the infrasound range starting at 19Hz and working downwards. I chose 19 as it's just below most peoples hearing range.

However, I am keen to find out what radio range it may fall in. I cannot find a chart to help me. Would 19Hz have a representative place in the AM radio range or would one need to look lower than AM?

If this is possible to assign a radio frequency to the low range of Hz I'd love to know a calculation or even see a chart depicting this.

Any help would be appreciated.

Kieron - UK

22967

It is true that sound frequencies less than 19Hz cannot be heard by humans, although they may be felt if the amplitude is great enough. But note that sound frequencies concerns the vibration of air or some material, while radio frequencies are electromagnetic waves, which are completely different than sound.

AM radio waves range between 535-1605 kHz. Those frequencies are much greater than the frequency of sound.

AC electricity creates electromagnetic waves between 50 and 60Hz.

## Solving frequencies for a wire

Topic: Sound from a String Equation

### Question

August 29, 2012

A wire under tensions vibrates with fundamental frequency of 256 Hz. What would be the fundamental frequency if the wire were half as long, twice as thick, and under 1/4 the tension.

Steel and silver wires of the same diameter and the same length are stretched with equal tension. What is the fundamental frequency of the silver wire if that of the steel is 200 Hz.

How can i solve this if there is no given value for the tension, length and mass.?

elphrane joy - Philippines

22865

First of all, you should look at Equation for Sound Created from a Wire instead of for a string.

You can solve the problem in pieces.

The equation shows that if the wire is half as long, then the frequency is twice as much. If you also double the thickness, then the freq is half as much. The combination results in the frequency staying the same.

Since the frequency is proportional to the square root of the tension, reducing the tension by 1/4 results in reducing the frequency by 1/2.

You will have to look up the densities of steel and silver wire to see how it affects the frequency.

## Numbers are switched

Topic: Sound from a Wire Equation

### Question

July 23, 2012

Somewhere on the webpage the following is stated:

Comparing the two frequencies, you get:

fC = (0.334/0.358)fS

fC = 0.933fS
In other words, changing the wire from copper to the less-dense steel will result in a frequency that is 0.933 of the original. Thus, if the frequency of the copper wire was 800 Hz, the frequency of the steel wire will be 746 Hz.

It should be reversed. If fS=800 then fC=746.

Do i get a free book now or what?

greetings from Holland,

Lucas - Netherlands

22793

Thanks for pointing out the mistake. I got the numbers switched and have corrected the values.

I can send you a free e-book copy of my Gravity book. Let me know if you want it as a PDF, EPUB, or MOBI (Kindle) file.

## Can sound cause a material to lose its strength?

Topic: Sound and Obstacles

### Question

July 14, 2012

When a matierial absorbs sounds due to the internal reflections or vibrations will strength of the matierial decreases or remains same?
If the the matierial is not porous or do not have any internal cavities or voids will the intensity of sound absorbed is same as the transmitted out from that matierial?

during reflections the matierial or obstacle vinrations?

Sriram - India

22781

When a material absorbs sound, its internal energy is increased. Usually, this does not affect the strength of the material unless the sound energy is so great to cause internal breakdown. Another case is if the sound frequency causes the material to resonate, such as sound causing a glass object to break.

When a material absorbs sound energy, the intensity of the sound is decreased. Some materials will transmit most of the sound through them, resulting in a very small decrease in sound intensity.

Reflected sound does not lose its energy, except for what it absorbed.

## Noise cancelling microphones for ships

Topic: Noise Cancellation

### Question

May 10, 2012

An interesting report, thank you
I am working on a special project that requires noise cancelling microphones for shipping. Two microphones are to be mounted in the wheelhouse of a super tanker. The microphones are connected to a mobile digital video recorder (yes images as well).
Ships as you know suffer from droning noises and vibrational sounds, I am looking for small noise cancelling microphones I can mount to a panel, that are tuned to human voice frequencies eliminating droning.

If you have any ideas on this unusual subject it would be great to hear from you. Kind regards David |M

David - UK

22641

One source for such microphones is Roanwell Corp. They make heavy-duty noise cancelling microphones that might suit your purpose.

Another possible company making such devices is Adpative Technologies.

I hope that helps. Best wishes with your project.

## Beats don't work for me

Topic: Sound Beats

### Question

May 1, 2012

I found this site very helpful for my class a few months ago. However, now it does not seem to work for me. When it asks me to click on the buttons, I don't see a button. Instead I see a big box with a question mark in the center. When I try to click on it, nothing happens.

James - USA

22628

Thanks for the feedback and for letting me know about the problem. I fixed things, so it should work fine now.

## Stopping furnace extractor fan noise

Topic: Noise Cancellation

### Question

April 22, 2012

Dear Ron: I have a noise problem that has become quite common. Where I live many people are replacing older natural gas furnaces with new high efficency model. These furnaces have an extractor fan that must operate before the furance can initiate combustion. These fans are vented through a high temperature rated PVC vent pipe. The internal surfaces of the pipe are very hard and tend to have an aplifying effect on the sound of the exhaust fan. In our jusisdiction is is permissab le to vent these furnaces about three feet above the ground. Is there currently any type of noise cancellation device available that would address this kind of noise. I am presuming that the noise will have a simple and predictable wave form. There is some variation with amplitude at start up and shut dowm but this is minimal. Thank you for any feedback you can give.

22606

This is one of the many annoyances that neighbors have to contend with. Manufacturers don't seem to consider the external noise such extractor fans cause. A baffling system, such as used in gasoline engine mufflers would probably reduce the noise considerably.

I think an active noise cancellation device would be difficult to use with these venting pipes. I don't think there is anything like that available commercially.

Another solution is to require sound barriers near and around the pipes.

It is a tough problem to solve. I hope these ideas help.

Next 10

## Summary

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