# speaker and wavelength

#### epilot

##### Member
Hello,

Today I read something about loudspeakers; there was something about relationship between beam width and the angular size of a sound beam generated by different speakers in size.

I read there, which there is a proportion between the size of the opening source of the speaker and the wavelength of the sound for beam width, which means; the larger the speaker opening the narrower the beam width we have.
I can not understand why?
Does anyone know why that ratio exists?
What the opening source of the speaker does here?

Thanks.

#### audioguru

##### Well-Known Member
Most Helpful Member
When the width of a speaker is half a sound wavelength, if you are not on axis then the sound from the near edge of the cone is cancelling the sound from the distant edge of the cone. 1" tweeters have beaming at about 15kHz but it is reduced when the cone is a dome.

#### epilot

##### Member
audioguru said:
When the width of a speaker is half a sound wavelength, if you are not on axis then the sound from the near edge of the cone is cancelling the sound from the distant edge of the cone. 1" tweeters have beaming at about 15kHz but it is reduced when the cone is a dome.
audioguru,
your explanation does not make any sense to me.

I have read that at a certain freq we can get a very tight beam if we have a speaker with a width of a small building.
In that paper I read that the reason is the relationship between the width of the speaker and the wavelength of the sound but I am not able to understand why if we hvae a larger speaker or a shorter wavelength we will get a tighter sound beam?

#### audioguru

##### Well-Known Member
Most Helpful Member
epilot said:
audioguru,
your explanation does not make any sense to me.
Then look at Speaker Beaming in Google. Many articles say the same as me.

I have read that at a certain freq we can get a very tight beam if we have a speaker with a width of a small building.
Simply calculate the length of a half-wavelength. You don't need to have a very tight beam at 20Hz. The required speaker is too big.

In that paper I read that the reason is the relationship between the width of the speaker and the wavelength of the sound but I am not able to understand why if we hvae a larger speaker or a shorter wavelength we will get a tighter sound beam?
The wavelength of 1kHz is about 34cm, and half the wavelength is 17cm. If a speaker has a diameter of 17cm or more and you are to its side, with it playing a 1kHz frequency then the near edge is one phase and its far edge is the opposite phase because of the extra distance. The sounds are out of phase and cancel.

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