# Simple Acoustics Question -- Which neighbor hears the other better?

• B
• alex282
In summary, Person 1 hears Person 2 better than Person 2 hears Person 1. This is due to the path of the soundwaves. However, it will mainly be due to signal to noise ratio at each end.

#### alex282

TL;DR Summary
Person 1 is in Apartment 1
Person 2 is in the alley between two blocks of apartments

If both people speak at the same volume, which one hears the other better?
There are two blocks of apartments separated by a narrow alleyway. Person 1 is in the middle of the room in Apartment 1 (first floor if you are in the UK and second floor if you are in the USA!) and Person 2 is on the ground outdoors in the alleyway.

If both people speak at the same volume, pitch and have the same hearing ability, which statement is the most accurate;
a) Person 1 hears Person 2 better.
b) Person 2 hears Person 1 better.
c) Person 1 and Person 2 hear each other equally as well.

If the answer is a) or b), how significant is the difference to which one person hears the other?

What is the simple explanation for the answer?

I have almost zero knowledge of acoustics but I am inclined to assume that Person 1 will hear Person 2 slightly better due to the path of the soundwaves, at least I hope this is the case and my neighbours do not hear me as clearly as I hear them when in the alleyway adjacent to my window

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alex282 said:
Person 1 is in Apartment 1
Person 2 is in the alley between two blocks of apartments
If both people speak at the same volume, which one hears the other better?
Person 1 hears Person 2 better. Because person 2 will have more local background noise than will person 1 in a more closed space.

sophiecentaur and phinds
Baluncore said:
Person 1 hears Person 2 better. Because person 2 will have more local background noise than will person 1 in a more closed space.
The principle of reciprocity is a pretty good one in radio communications and it should also apply in acoustics. However, as @Baluncore says, it will be mainly a matter of signal to noise (or interference) ratio at each end.

Yes, what they said.

Much depends on what, if any, other sounds are and where they come from. Also how loudly each is speaking and how good their hearing is. If everything is the same (reciprocal), then the sound waves normally should propagate identically regardless of direction.

However, there are special materials, or circumstances, where that isn't true. You can search for "acoustic diode" or similar to learn more.

https://phys.org/news/2013-11-acoustic-diode.html

The Rayleigh reciprocity relation, described in his book "Theory of Sound". For radio waves we can use the Rayleigh-Carson reciprocity theorem.

sophiecentaur
Another confounding influence would be the gender of the participants, and their personal relationship.

DaveE
There is another answer to this question. It will be the grumpier / older neighbour who is disturbed first.

## 1. How does sound travel between neighbors?

Sound travels through the air in the form of vibrations. When a sound is made, it creates pressure waves that travel through the air and reach our ears, allowing us to hear the sound.

## 2. What factors influence how well a neighbor can hear the other?

Several factors can influence how well a neighbor can hear the other, including the distance between the two neighbors, the type of material between them (such as walls or windows), and the loudness of the sound being produced.

## 3. Why is it sometimes easier to hear neighbors through walls than through open windows?

Walls are more effective at blocking sound than windows because they are thicker and denser. Windows, on the other hand, are often made of thinner materials that do not block sound as well.

## 4. How can noise from neighbors be reduced?

Noise from neighbors can be reduced by using materials that absorb sound, such as curtains or carpets, or by creating a physical barrier between the two spaces, such as a soundproof wall.

## 5. Is there a way to measure how much sound travels between neighbors?

Yes, there are various tools and techniques that can be used to measure sound levels, such as decibel meters. These measurements can give an accurate representation of how much sound is traveling between neighbors and can be used to determine the effectiveness of soundproofing measures.