20
The reflecting surface must be sufficiently smooth and shaped such that the sound is reflect back and not dispersed. Sound travels at approx 340 metres per second and the average human brain easily can distinguish sounds that are 1/2 second apart. That means the sound must travel at least 170 metres so that the reflecting surface must be half that distance away. While a greater distance will create a more distinctive echo, the strength of the returning sound fall off rapidly (at twice the square of the distance to the reflecting surface). In normal circumstances 170 metres (= approx 500 feet) is a good distance. A cave or convex reflecting surface will allow a greater distance.
Santa Catalina sings about 26 miles. If you miss the train I'm on...you'll hear the whistle blow a hundred miles
(Distance) x (Time) is a number that has the dimensions of [ L T ]. It would be expressed in units such as "kilometer-hours" or "foot-seconds". It has no physical significance and is altogether quite meaningless. Which may be a big part of the reason that we never hear it used.
There is no indication as to how long the first trump will last, but assuredly it will last long enough for all peoples of the world to hear it.
200 ft
a lion can at least hear up to about 7 feet away
The minimum distance for an echo to be heard is approximately 17.2 meters (56.4 feet) from the source. This accounts for the time it takes for sound to travel to the obstacle and then reflect back to the source for the echo to be perceived.
On average, a person can hear sounds underwater up to a distance of about 60 meters (200 feet). This distance may vary depending on water conditions, such as temperature, pressure, and clarity.
http://wiki.answers.com/Q/A_horn_must_be_loud_enough_to_hear_within_how_many_feet"
The distance at which a human can hear sounds depends on various factors such as the volume of the sound, the environment, and the individual's hearing ability. Generally, a human can hear sounds from a distance of up to 20 feet away in a quiet environment. However, this distance can vary significantly in different situations.
Humans can typically hear sounds in their environment up to a distance of about 20 feet, depending on factors such as the volume and frequency of the sound.
Depends on the quality of the sound. The minimum distance to hear an echo will be partly based upon the observers ability to resolve different sounds (i.e. so that they can distinguish between the actual noise, and the arrival of the reflected sound - a little 100 year old lady may not be as good as a 15year old!). This will vary between observers, as their auditory reaction times vary In the perfect Physics world though: Assuming a sharp sound (like a gunshot) the minimum distance (d=vt) to hear distinct echo is 17.2m considering the speed of sound to be 344ms. In general the "minimum echo distance" is always equal to half a wavelength from the reflector.
Depends on the quality of the sound. The minimum distance to hear an echo will be partly based upon the observers ability to resolve different sounds (i.e. so that they can distinguish between the actual noise, and the arrival of the reflected sound - a little 100 year old lady may not be as good as a 15year old!). This will vary between observers, as their auditory reaction times vary In the perfect Physics world though: Assuming a sharp sound (like a gunshot) the minimum distance (d=vt) to hear distinct echo is 17.2m considering the speed of sound to be 344ms. In general the "minimum echo distance" is always equal to half a wavelength from the reflector.
yes, you can hear planes at 35000 feet.
No, cats hear very well with their ears. They do not hear with their feet. They may also react to anything that causes the ground to rumble, and may feel that with their feet, but that is not the same as hearing with their feet.
5 feet