As for me, the intervals between the sounds is too which the sounds is too short (meaning it goes 'too fast' for me). In my case, I would play the 'music' version for preference of doing it at a rate it can enjoy rather than rushing it. For some others, it may not be fast enough, so they opt for the music version so they can do it faster. It all comes down to what is comfortable.
This was the case for me, Zakyrus. I really like Master Lin's Voice on the Small Universe audio, so I ordered the hour-long CD, hoping it would be a bit slower, but it isn't.
However, The Heart Sutra Chant CD of Master Lin's is perfect for me. I still "hear" the Ommmm and Moaaah from the Small Universe CD "in my mind" and I "hear" Master Lin as an instrument (on the Heart Sutra CD) and his chanting as music, rather than words. I do not understand any of the words so this works for me.
This body seems to like to breathe, while meditating, at four breaths per minute and it turns out that the Heart Sutra Chant in Master Lin's voice lasts one-half "round" of Small Universe at my rate of breathing, from the lower dantien to the spinal-cord-of-neck area, one more sutra-chanting lasts from the spinal-cord-of-neck area back to the lower dantien. So for every "round" of the Small Universe I hear the Master Lin's Heart Sutra Chant twice, precisely.
On the Heart Sutra Chant CD package, Master Lin says,
The Heart Sutra is Buddha's perfect expression of unconditional love, compassion and forgiveness.
It contains the most powerful messages in the universe to help you raise your energy to a higher spiritual level through the doctrine of emptiness.
The Heart Sutra is the shortest sutra in Buddhism and the most highly regarded. It is considered the summation of the wisdom of Buddha. I chant the Heart Sutra regularly in my meditation.
By listening to it daily your energy system will be tuned in to its vibration more and more closely. The closer the vibration of your energy comes to the vibration of the Heart Sutra the greater the guidance and understanding you will receive from the universe.
You may play this chant at any time, while you are sleeping or in the background as you go about your daily life. It is especially helpful to play the Heart Sutra chant during a healing session or during longer meditation for spiritual cleansing.
In the beginning of my listening to Master Lin's chanting of the Heart Sutra during my Small Universe meditations, there was a lot going on: reverse-breathing, the Ommmm and Moaaah "sounds in my mind," the attention moving from area to area with each breath, and the chanting of Master Lin in words I don't understand. It was like learning to ride a bike and became just as easy, pretty soon.
I'm way over a hundred days at it now and, for me, the combination of the Small Universe and Master Lin's Heart Sutra chanting is kind of a spiritual double-whammy - it took my meditation to a new level.
David