Here is a wonderful article that goes in depth to the science of sound.
I work with Crystal Tones Alchemy Singing Bowls, they are top notch in intention and energetics.
By Sam Gileadi, Sound Engineer for Crystal Tones
“There are several elements to the sound of the Crystal Singing Bowls that make them incredibly suited for meditation and sound healing purposes. Unique to the Crystal Singing Bowls is the presence of what are called vocal formants. Understanding what formants are is as simple as singing vowels such as ‘ahh’ or ‘oooh.’ Formants are the elements of sound that makes vowels sound like they do. The bowl or bell shape gives the sound similar characteristics to the human voice. This quality is why they are known as singing bowls. The use of both bells and choirs is a well-known part of many religious and spiritual ceremonies. Studies have also shown that the human mind reacts positively to the sound of singing. One need only picture a mother calming a child with the sound of her voice, or a yogi chanting OM to understand how deeply we react to vowel sounds and singing.
They are excellent tools for creating natural binaural beat tones. Scientific studies and a multitude of experiences by practitioners suggest that the use of binaural beats is an effective way to treat anxiety and similar disorders, and to achieve a meditative mental state The Crystal Singing Bowls offer a unique advantage over beats created by synthesized tones because the sounds are created acoustically. The sound is natural, more complex, and more pleasant to listen to. Importantly: when two bowls are used, the process of entrainment occurs naturally between the two as they feed back between each other and cause each other to resonate towards a state of equilibrium.
The Singing Bowls generate not one single note, but several. Musically speaking these are known as the fundamental note (lowest note) and the harmonics. The harmonics generally follow musical intervals, so playing a single bowl has similarities to playing a chord on a piano. What the ‘chord’ might be depends on the construction of each individual bowl. In some cases the harmonics are close enough to each other in pitch that they add a natural vibrato to the sound, following the same principle of interference beating that makes binaural beats possible. Think of a piano player using major or minor chords to make their audience feel different emotions. Another example would be Tibetan monks overtoning so as to create multiple tones with their voices.
The addition of metals or gemstones to the Alchemy Crystal Bowls adds another dimension to the sound. They add their own qualities by dampening or filtering the pure crystal sound. Especially in the case of metals such as gold or platinum, they also add the resonant characteristics of these materials. For example, with a Gold Alchemy bowl, the sound will be smoother and slightly metallic. Consider how a classical composer might use the softer sound of a violin or cello to evoke feelings of nostalgia, or she may employ the more metallic sound of brass instruments to give more energy to the music. The alchemy elements subtly alter the sound for a similar range of effects.
Each of these elements on their own has beneficial effects to human psychology. The Crystal Singing Bowls take all these different elements, each with positive effects, and integrate them into a single, holistic system that is rooted in ancient tradition. A skilled bowl player takes advantage of all of these elements. Through proper playing technique one can emphasize or eliminate any of the tones that the bowls are able to make. This means that by means of biofeedback, or reacting to how the player feels and what they hear and changing the sound accordingly, she can tailor the experience of playing the singing bowls according to how she feels.”
Sound Engineer for Crystal Tones