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

[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

 

[Baluncore]

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]

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.

 

[DaveE]

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

 

[tech99]

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

 

[Baluncore]

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

 

[sophiecentaur]

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