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I was sitting close to a speaker and I could feel the sound coming from it all over my body, especially in my heart, and it pounded with the loud beats of the music.
Was my heart pounding because of the excitement at listening to the music or was I really feeling the sound in my heart and all over my body?
I have some understanding that it is all about sound waves & acoustics (bass/low & high pitch/low and high notes etc.) but it is not clear to me.
I hope I have correctly framed my question.
Sound is a pressure wave. Continuous sound is a continuous stream of high pressure fronts followed by low pressure fronts. The louder a given sound is, the higher the difference in pressure between a crest and trough; pressure is the amplitude of the sound wave. Furthermore, the volume of a sound is also dependent on frequency. Humans are not as sensitive to high frequency and low frequency sounds. So, for example, a song with a lot of bass has to be played at a higher amplitude in order to be just as loud.
The threshold of pain (that is, the loudest a sound can be before most people experience pain) is about 100 phon. The figure below from Wikipedia shows how that relates to amplitude and frequency.
The red lines show constant volume. The abscissa is frequency and the ordinate is sound pressure level.
As you can see, for 100 phon, the low frequency sounds go up to $130$ dB. I'll spare you the explanation from Wikipedia, but this translates to the high pressure fronts being about $150~Pa$ above the standing air pressure and the low pressure fronts being about $150~Pa$ below average. That means from high to low pressure, you experience a $300~Pa$ difference. That may not seem like much given that the sea level pressure is around $101~kPa$, but it should be noted that $100~Pa$ is the pressure from a strong breeze and $300~Pa$ is about the lung over-pressure of a normal breath. So it's not surprising that you feel a pulse every time the music plays a strong bass. Another way to look at it is it's like you're lying down and every time a bass note is played, your whole body is covered with 2 layers of US quarters, which are removed once the note stops again. Doesn't sound like much, but you'd definitely notice it.
Along with your pounding heart, you're also experiencing the effects of resonance. In simple terms, there are certain frequencies of sound waves which correspond to the "natural" vibration frequency of your bones. At these frequencies, your bones vibrate with a greater amplitude than other frequencies, and you can think of it as "tapping" into the vibrational energy of your bone system. So some parts of your body may seem to vibrate when you stand next to the speaker which is emitting sound waves (typically bass-enhanced sound), and I'm sure you'll be less worried about in now. You can read more about resonance here: http://en.m.wikipedia.org/wiki/Resonance
was I really feeling the sound in my heart and all over my body?
It is definitely possible to feel sound. This occurs when the pressure is high enough and the frequency is low enough for the sense of touch. The heart can definitely produce a sensation of pain, perhaps also that of external pressure albeit with a rather low sensitivity.
In simple words its just like if you are standing in-front of a small wave you won't be affected that much when that wave hits you but if its a large one then you will definitely be affected a lot, its just all about force and pressure, the louder and bassy it gets the more the pressure and force that hits your heart mind ears and almost every part of your body feels the sensation. I'll advice that it should not be kept at levels that make you feel all of these feelings and especially a thumping feeling to the heart.
