Why are there no echos in a house?

Answer 1

You have to make a distinction between "echoes" and "resonance," because there is a difference. What you are referring to is actually "resonance," but also, the term "house" could include a number of stately homes, where there is often considerable resonance in marble hallways, ballrooms, courtyards and music-rooms etc.

So having shot you down in flames, let's look at what you really mean, and look for a few answers.

All materials absorb sound, but some absorb very little, whilst others absorb almost all sound. When materials absorb only a little sound, we get reflections from things like stone, timber and metal surfaces. These materials have a "low absorbtion coefficient" and therefore reflect sound-waves. Large old churches are usually resonant because they are made from stone and timber, which are "low absorption-coefficient" materials.

Where there are sufficient reflections of sound waves, we end up with resonance, which in the case of certain rooms, can be anything up to 10 seconds before sound finally dies away to the point that it is inaudible. In the UK, a classic example would be LIverpool Cathedral (11 secs reverberation) and in the US, perhaps St.John-the-Divine, NY cathedral. (9 seconds).

Live music always sounds best in a "live" or resonant acoustic, and the maginificent sound of an organ & choir in the above two buildings, owes much to the acoustic resonance of them.

Oddly enough, size is not the biggest factor in acoustic resonance, but the shape of a room is of critical importance. Certain type of shape ancourage resonance, such as domes, barrel ceilings, buildings twice as long as they are wide and high (the classic "double-cube"....two squares set side by side). Hence, the great cathedral of St.Paul's, London, has a huge resonance (10 seconds) , due to the mathematical proportions and the existence of a large central dome; all made from hard, reflective materials.

Leaving aside very large, old stately-homes and mansions, most homes have square-ish rooms and low ceilings: a shape which does not encourage resonance. Add to this the use of very sound absorbent materials, such as felt, wool, insulating materials, cloth, plaster-board, various plyboards.....all in the form of furniture, carpets, sofas, curtains (etc etc)......it amounts to a room which is unable to sustain resonance, because resonance requires multiple reflections of sound waves, which absorbent materials do not allow.

As others have pointed out, even a room of modest size will "echo" a bit when all the soft materials and furnishing are removed.

So, in a nutshell, you DO hear echoes in any room, but what you do not hear are huge numbers of multiple echoes, which are the components in what we term "resonance," because they are absorbed by the soft furnishings and materials.

The more you learn about acoustics and resonance, the less you realise you actually know, and many very clever people spend a lot of time trying to get the acoustics of stadiums, halls and meeting places just right, but they often do not succeed.

If you wish to know more, then look up the "Arup Associates" web-site, which includes mp3 demonstrations of how different rooms and materials affect sound.

I hope this helped.

Answer 2

Empty houses sound very echoey. But in a full house all the rugs and couches and things tend to muffle the sound. But showers usually have good echoes. That is why people like to sing in the shower. But those echoes are quick. You don't hear, "HELLO------hello", you hear, "HhEeLlOo" because the walls are so close that the sound comes back really soon.

Answer 3

Echo is dependent on sound reflecting off of a surface. Most homes are made of materials that are more likely to absorb sound than to reflect it: wood, sheetrock, wallpaper, and paint will all absorb sound.

When the house is furnished, the furnishings and floor coverings are going to absorb sound, too.

FWIW, in many large cavernous buildings constructed of stone or stone-like materials (e.g., cement or brick), if the building is empty and it is very quiet, you can hear a very definitive echo. That's because the sound is being reflected by non-absorptive materials.

FWIW, the so-called "stealth" technology that's used in the B-2 bomber and the F-117 stealth fighter is based at least in part on use of materials that absorb rather than reflect radar beams.

Answer 4

There are echos in a house but they bounce back so quickly you can't distinguish them from the original sound. The speed of sound is greater than 900 ft/second so any closer than that and you won't get an echo.

Answer 5

The size of the room does not matter when it comes to creating echoes. The stuff in the room is what matters. In most rooms of our house, we have lots of soft objects like couchs, chairs, carpet, curtains, pillows, etc. which absorb sound energy and do not let it reflect. In some rooms, like the bathroom, you are more likely to hear echoes, as you have a lot of hard objects like sinks, tile, bathtubs, and showers all of which would not absorb sound energy.

I sang for three years with a touring a capella choir, and how "live" a room is (how much echo there is) is very important. Spaces with lots of hard surfaces like tile, stained glass, marble, wood seats, stone, or concrete are much easier to sing in as there is much more echo. This is compared with rooms with thick carpet, padded chairs, soft tile ceilings, heavy curtains, and sound absorbing walls, which have no echo. The size of the room or space really didn't matter as much as what was in the room or space.

Answer 6

There are echos. It's just they happen too quick for you to sense. Even with a room that is 50 ft long it takes less tha 1/10th of a second for sound to travel from one end of the room to the other and back. That means the sound would have to be very short duration in order for a noticable break in the sound pattern.

Answer 7

Your premise is false:

This morning in the shower, I clearly heard echoes of my singing. Bathroom tiles reflect sound better than most wall and ceiling surfaces in the house, so you can hear the sound echoing for a while.

Answer 8

You need about 60 feet of space to hear an echo.

Answer 9

If the house has plenty of soft furnishings then the bouncing soundwaves are diffused. If you notice, most echoey places have lots of hard or shiny surfaces.
That's why recording studios have sinusoidal foam tiles on the walls. To diffuse as much echo as possible.

Answer 10

take everything out of your house then tell me there are no echos in there