# Contradiction in Phase of reflected sound

• Vivek98phyboy
In summary, while studying sound waves in organ pipes, it was noted that there is a contradiction in the fact about the phase of reflected waves as described in different sources. Some sources state that the reflection from a rigid surface is in phase, while others say it is 180° out of phase. However, all sources agree that compression returns as compression and rarefaction returns as rarefaction from a hard surface. This discrepancy in phase change is also evident when referring to online portals on the topic. Despite initial thoughts that this could be due to discussing pressure and displacement waves, which have a 90° phase difference, it is still unclear why there is a 180° phase difference between the two descriptions.
Vivek98phyboy
Homework Statement
While studying the fundamentals of sound waves in organ pipe, I noted that the fact about phase of reflected waves is contradicting while referring multiple sources
Relevant Equations
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While studying the fundamentals of sound waves in organ pipe, I noted that the fact about phase of reflected waves is contradicting while referring multiple sources

This book of mine describes the reflection from a rigid surface/closed end to be in phase

Whereas this one describes the reflection from a closed end to be 180° out of phase

Yet, both the books says that, "compression returns as compression and rarefaction returns as rerefaction, from a hard surface" and I found it to be true in all the sources i referred. But this phase change described by them is completely contradicting with each other. I found the same issue while referring some online portals on this topic.

Why are these books contradicting each other?

Initially I thought that one of them might be discussing about pressure wave and another one about displacement wave, as they have a 90° phase difference at any point of time. But even in such case, a phase of difference of 180° shouldn't be produced, right?

Vivek98phyboy said:
one of them might be discussing about pressure wave and another one about displacement wave, as they have a 90° phase difference at any point of time.
Quite so.
The pressure and displacement functions can be a quarter cycle out of phase in opposite directions, so the two waves can be in phase for pressure but half a cycle out of phase for displacement.

## What is "Contradiction in Phase of reflected sound"?

"Contradiction in Phase of reflected sound" refers to the phenomenon where sound waves reflected off of a surface have a different phase than the original sound waves. This can result in interference patterns and changes in the perceived sound quality.

## What causes "Contradiction in Phase of reflected sound"?

There are several factors that can contribute to "Contradiction in Phase of reflected sound", including the angle of incidence and reflection, the distance between the sound source and the reflecting surface, and the acoustic properties of the surface itself.

## How does "Contradiction in Phase of reflected sound" affect sound quality?

"Contradiction in Phase of reflected sound" can result in changes to the perceived sound quality, such as an increase in echo or a decrease in clarity. This can be especially noticeable in enclosed spaces with many reflective surfaces, such as concert halls or recording studios.

## Can "Contradiction in Phase of reflected sound" be corrected?

Yes, "Contradiction in Phase of reflected sound" can be corrected through various acoustic treatments, such as adding sound-absorbing materials to reflective surfaces or using diffusers to scatter sound waves. Additionally, careful placement of speakers and acoustic panels can help minimize the effects of phase contradiction.

## How is "Contradiction in Phase of reflected sound" relevant to everyday life?

"Contradiction in Phase of reflected sound" is relevant to everyday life in various ways, such as in the design of buildings and performance spaces, the production of music and film, and even in the design of everyday objects like headphones. Understanding this phenomenon can help improve sound quality and create more enjoyable listening experiences.

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