Shamans used 110 Hertz in order to trance ancient people in temples.These frequencies are obtained by whistling in Chavin de Huantar (Peru). (left) The same frequency also appeares in The Ħal Saflieni Hypogeum at Malta.

The Ħal Saflieni Hypogeum was built 6,000 years ago (below)  and Chavin de Huantar was built 3500 years ago. Why shamans used the same frequency in different temples and different age? The Hypogeum was built as underground chambers in Malta. Voice chamber has an echo feature. A person (probably shaman) was whistling from the Oracle Room creating 110 Hertz using PUTUTU. Resonance created by the whistle and temple walls made people go in trance with pututu. (Oracle Room: This is roughly rectangular and one of the smallest side chambers. It has the peculiarity of producing a powerful acoustic resonance from any vocalization made inside it. This room has an elaborately painted ceiling, consisting of spirals in red ochre with circular blobs. Source: wikipedia)

The question is why people go to sleep trance in 110 Hertz?

Because 110 Hertz deactivates speaking part in human brain and opens social behaviour and change temperament.

Experiments done in the temple by  UCLA shows that 110 Hertz works as explained above in human brain. [1] 

So, why brain is deactivated at 110 Hertz?

According to UCLA 110-111 Hertz gives courage and well-being (cell renewal) to humans. 110 Hertz is the frequency which is associated with both the stomach and the ovaries. (In a pilot study in 2008 by Dr. Ian Cook from UCLA)

You can listen to 110Hz in the following link:  

S. Vedat Karaarslan