Last visit was: 18 Nov 2025, 18:14 It is currently 18 Nov 2025, 18:14
Home
GMAT
Messages
Tests
Schools
Events
Rewards
Chat
My Profile
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
Medium|   EXCEPT|   Medium Reading|   Science|      
User avatar
Sajjad1994
User avatar
GRE Forum Moderator
Joined: 02 Nov 2016
Last visit: 18 Nov 2025
Posts: 17,289
Own Kudos:
49,291
Given Kudos: 6,179
GPA: 3.62
Products:
GMAT Club Tests Forum Quiz
Posts: 17,289
Kudos: 49,291
Though an echo is a fairly simple acoustic phenomenona reflection of 27 Jan 2025, 12:26
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Question 1
00:00
Start Timer
Pause Timer
Resume Timer
Hide
Show
History
Error Log
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

(N/A)

based on 1 sessions

0% (00:00) correct 100% (00:26) wrong

History

Date
Time
Result
Not Attempted Yet
Question 2
00:00
Start Timer
Pause Timer
Resume Timer
Hide
Show
History
Error Log
B,C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

(N/A)

based on 1 sessions

0% (00:00) correct 100% (00:10) wrong

History

Date
Time
Result
Not Attempted Yet
Though an echo is a fairly simple acoustic phenomenon—a reflection of sound waves off some hard surface—it occurs only under very specific circumstances. Imagine a listener standing at the sound source. The reflecting object must be more than 11.3 meters away from the sound source, or the echo will return too soon to be distinguishable from the original sound. A reflecting object more than about 170 meters, on the other hand, will rarely produce an audible echo, since sound dissipates with distance. Further, multiple surfaces each reflecting the same original sound to the same listener will likely not produce an echo, but a reverberation, a persistent sound gradually decreasing in amplitude until the listener can no longer hear it. Common though echoes are then, it is unsurprising that some sounds seem to produce no echo.

A centuries-old tradition holds that a duck’s quack does not echo. Scientists in the Acoustics Department of the University of Salford set out to test and explain this claim. They recorded a duck, Daisy, first in an anechoic chamber filled with sound-absorbing fiberglass wedges, then in an echo chamber with the acoustical properties of a small cathedral. The sound of the duck quacking in the anechoic chamber was clearly different from the sound of the duck quacking in the echo chamber, but the researchers acknowledged that it would be very hard to recognize an echo in the latter recording without having very recently heard the former. Partly this is because a quack isn’t a single burst of sound, but fades in and out, so that the beginning of the echo might blend with the end of the original sound. Partly it is because a quack is just not very loud. The Salford researchers also speculate that most people may simply not
encounter ducks in proximity to reflectors such as buildings or mountains. A further complication, though one the researchers leave unremarked, is that people generally hear ducks in flocks, where one quack might be indistinguishable from the echo of another.
1. According to the passage, all of the following make an audible echo unlikely EXCEPT

(A) a reflecting surface too close to the original sound
(B) a reflecting surface too far from the original sound
(C) multiple reflecting surfaces
(D) multiple listeners
(E) sound-absorbing materials


Consider each of the answer choices separately and indicate all that apply.

2. The passage suggests that which of the following would propagate echoes?

A. An anechoic chamber
B. A cathedral
C. A mountain

ShowHide Answer Question #1
Official Answer
D
ShowHide Answer Question #2
Official Answer
B,C
User avatar
Sajjad1994
User avatar
GRE Forum Moderator
Joined: 02 Nov 2016
Last visit: 18 Nov 2025
Posts: 17,289
Own Kudos:
49,291
Given Kudos: 6,179
GPA: 3.62
Products:
GMAT Club Tests Forum Quiz
Posts: 17,289
Kudos: 49,291
Though an echo is a fairly simple acoustic phenomenona reflection of 03 Feb 2025, 13:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
OE

1. According to the passage, all of the following make an audible echo unlikely EXCEPT

The passage claims that the reflecting surface must be far enough away so that the sound of the echo is distinct from the original sound, but not so far away that the sound is completely dissipated. You can use that information to eliminate (A) and (B). The passage also claims that multiple reflecting surfaces are apt to produce a reverberation rather than an echo, so cross off (C). The anechoic chamber with “sound-absorbing fiberglass wedges” is presented as a contrast to an “echo chamber,” so (E) is also out.

Answer: D
User avatar
Sajjad1994
User avatar
GRE Forum Moderator
Joined: 02 Nov 2016
Last visit: 18 Nov 2025
Posts: 17,289
Own Kudos:
49,291
Given Kudos: 6,179
GPA: 3.62
Products:
GMAT Club Tests Forum Quiz
Posts: 17,289
Kudos: 49,291
Though an echo is a fairly simple acoustic phenomenona reflection of 03 Feb 2025, 13:43
Kudos
Add Kudos
Bookmarks
Bookmark this Post
OE

2. The passage suggests that which of the following would propagate echoes?

The second paragraph notes that the echo chamber is constructed with “the acoustical properties of a small cathedral” precisely in order to create echoes; this supports the second statement. Mountains, along with buildings, are offered in the second paragraph as examples of the sort of reflecting surface likely to bring about an echo, which supports the third statement. The first choice is wrong because the passage describes an “anechoic chamber” as filled with “sound-absorbing fiberglass wedges,” which are the opposite of the sound-reflecting objects required to propagate echoes.

Answer: B,C