Here is part 6 of the series I am writing on the science behind music in “Saamagaana – The First Melody“, a monthly magazine on Indian Classical Music. The intent is to help readers understand a bit more about the science behind music and musical instruments and to enhance their appreciation of the same.
This is from the September 2015 issue of the magazine
Sounds, spaces and singing
Confined spaces give one a feeling of being surrounded by music, but step out into the outdoors and what you hear changes, writes R RAMKUMAR
I went to a violin concert in the morning in a park. The volume seemed a lot lower than in a chamber concert by the same artiste a week back. Why?
Let us assume that the level of sound amplification was similar in both cases.
A chamber concert mostly happens in a room or in a small hall. Sound from the loudspeakers or from the violin directly travels to your ears. In addition, the sound that doesn’t come to your ears directly gets reflected from the walls, the ceiling, the floor, etc., and also reaches you from all directions. The violin thus sounds louder and you also get a feeling of being surrounded by music.
In an open space, like that in a park, you get the sound that reaches you directly and probably the sound that gets reflected from the floor. The rest of the sound dissipates in the open space. Thus the volume seems a lot lower.
Doesn’t a large auditorium also have a lot of space like a park? Why then are the sounds loud enough in the former and not the latter?
An auditorium, however large it might be, is still different from a park in that it is a closed space. This means that even though the direct sound that reaches you in a large auditorium might be a small percentage, the rest of the sound gets reflected from the walls, from the seats around you and from other surfaces and at least some percentage of it comes back to your ears. How the surfaces in the auditorium reflect this sound determines how the auditorium sounds.
In an acoustically well-designed auditorium, great care is taken that this “indirect sound” is handled properly. The loudspeakers in such auditoria generate a direct sound that is comfortably loud. This direct sound is complemented with early reflections which reinforce the direct sound and help us hear the same better. Our hearing system treats them as part of the same sound, thus the reinforcing action.
Late reflections (for example, echoes) are distinguishable from direct sound and, as their name suggests, arrive late after getting reflected from a surface farther away. Good auditoriums are designed to either absorb these or disperse these into quieter reflections that do not interfere with the understanding of what is being performed.
Does this reflection of sound in the auditorium also affect the performers?
Yes. It definitely could. Let us take echo as an example. It usually happens from the back wall of the auditorium. Since the performers on stage are usually the farthest from the back wall, the echo for the performers would be the most delayed. Echoes affect the perception of timing in what is being performed. The performers can get affected if the echoes are delayed and strong enough.
Why does my singing usually sound better in my bathroom than in my living room?
The space in a bathroom is usually less than that in a living room. The surfaces are also usually covered by tiles and are hard. This means that the sound you create keeps bouncing off from the surfaces, reinforcing and lasting longer. Contrast that to your living room that may have a lot of furniture and curtains. These absorb sound and the sound dies away quickly. Thus your singing usually sounds better in the bathroom.
(Image courtesy: Saamagaana – The First Melody)