I am providing the answer based on Patanjali Yog-Sutras. Here Patanjali is describing our mind in detail . Pantanjali is saying that thought waves constantly arose in our mind , our senses are constantly giving our mind information from outside world. Because senses are attached to outside material world. Some of these thought waves are pleasant as well as unpleasant .
So constant attachment to the outside world and to material desires is the basic reasons these -reverberations occurs in our mind. Our memory is also crucial part in this process.
Yoga is the control of thought-waves in the mind. Sutra 2
When an event or object in the external world is recorded by the
senses, a thought-wave is raised in the mind. The ego-sense identifies
itself with this wave. If the thought-wave is pleasant, the ego-sense
feels, "I am happy"; if the wave is unpleasant, "I am unhappy."
In order to become enlightened we must bring the thought-waves under
control, so that this false identification may cease. The Gita teaches
us that "Yoga is the breaking of contact with pain." There are also
minds which, though they possess a certain degree of energy, can only
dwell on what is pleasant; they shrink away from the disagreeable
aspects of life. But every mind, no matter what its present nature,
can ultimately be disciplined and transformed—can become, in
Patañjali’s phrase, "one-pointed" and fit to attain the state of
perfect yoga. Knowledge or perception is a thought-wave (vritti) in
What is the reason of these reverberations, lastly?
The reason Paatanjali is giving is our mind and nature of it . As thought waves constantly arose in our mind just like ripples these thought waves are the reasons of this reverberations , which arose because our attachment to the external world / desires ,and the sensory instructions constantly send by our organs i.e pancha Indriyas. And our Memory.
वृत्ति सारूप्यमितरत्र ॥4॥
vṛtti sārūpyam-itaratra ||4||
At other times, when he is not in the state of yoga, man remains
identified with the thought-waves in the mind.
So normally these thought waves or reverberations occurs constantly in
our mind , when not in yoga.
वृत्तयः पञ्चतय्यः क्लिष्टाक्लिष्टाः ॥5॥
vṛttayaḥ pañcatayyaḥ kliṣṭākliṣṭāḥ ||5||
There are five kinds of thought-waves---some painful, others not
The idea that we should ultimately have to overcome even
those thought-waves which are "good," "pure" and "truthful" may at
first seem shocking to a student who has been trained in the Western
approach to morality. But a little reflection will show him that this
must be so. The external world, even in its most beautiful appearances
and noblest manifestations, is still superficial and transient. It is
not the basic Reality. We must look through it, not at it, in order to
see the Atman. Sutra 4 -5
See the involvement of memory function in occurance of reverberations in our mind in below sutra.
अनुभूतविषयासंप्रमोषः स्मृतिः ॥११॥
anu-bhūta-viṣaya-asaṃpramoṣaḥ smṛtiḥ ||11||
Memory is when perceived objects are not forgotten, but come back to
consciousness. Memory is a kind of secondary thought-wave. A wave of
direct perception causes a smaller ripple or series of ripples
How one can stop the play of these sounds?
In the sutra 15 Patanjalii is giving us the advice about how to control the reverberations or thought wave arising in our mind through Non-attachment.
दृष्टानुश्रविकविषयवितृष्णस्य वशीकारसंज्णा वैराग्यम् ॥१५॥
dṛṣṭa-anuśravika-viṣaya-vitṛṣṇasya vaśīkāra-saṃjṇā vairāgyam ||15||
Non-attachment is self-mastery; it is freedom from desire for what is seen or heard.
Also Patanjali in above sutra is saying that, " realizing that thought
waves created in our mind from information send by our sense organs is not reality
but superficial and transient" , is another way to stop these sounds or
reverberations. And yoga is the way to do this.