Man's physical universe

xanabras

464 ENERGY MAY BE PROPAGATED BY VIBRATIONS

One Can Learn an Important Lesson in Acoustics from the Bathroom.

It is a well-known fact that people like to sing or whistle in a bathroom.

Nearly everyone sounds like an artist (to himself) in a bathroom

because the reverberations in

the bathroom enable the singer to hear

his own voice as it is reflected back to him with little loss of energy.

The result of being unable to hear one's self sing results in tension

and nervousness that decrease vocal efficiency. In the attempt to

fill a hall with one's voice, one is apt to force it into too high a pitch.

A modern device to aid artists utilizes public-address units directed

toward the artist so that he can hear himself sing.

A room which is well adapted to speech will be too dead for music,

because the musician needs reverberation in order to blend one tone

into another. Music halls should be so constructed that the wall back

of the music source will act as a sounding board, while the wall behind

the audience should absorb sounds. Large areas of wood nailed on

furring strips of variable spacing permits them to vibrate in

response

to quite a range of low-frequency vibrations, thus amplifying the low

frequencies. These wooden surfaces should be given a highly polished

finish so as to reflect the high-frequency tones, which otherwise may

be readily lost by absorption.

Acoustics Should Be an Important Consideration in Building a Modem

Dwelling.

In building a modern home, many acoustical problems are presented.

Noises from bathrooms, kitchens, and laundries should not be transmitted

to other rooms in the house. The blare of a radio in one room

should not be allowed to bother the occupant of another room. There

should be a room where it is possible to play various musical instruments

without bothering other occupants of the house or annoying

the neighbors.

Special types of acoustical boards may be used on the ceilings of

kitchens or laundries to deaden sounds. Ordinary lath and plaster

partitions often act as diaphragms or resonators to transmit sounds.

Walls may be made sound-proof by building two or three thin partitions

which are separated by absorbing materials such as cellulose

building-boards. Walls constructed of hollow concrete blocks made

from porous aggregates insulate against sound as well as heat. In

general,

the same types of material that are used for heat insulation

also serve for sound-deadening.

Porous material like hair felt, cellulose fibers, and textile materials

reflect only a small amount of sound and absorb relatively large

amounts. Solid plaster reflects over 97 per cent of sound waves.

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