The name of this Pranayama originates from Sanskrit word Bhramar that means bumblebee. While performing this Pranayama a buzzing sound, typical of bumblebee is produced from the nostrils.
 

Method for Bhramari Pranayama:

Sit down in Padmasana, Siddhasana or Vajrasana. Now inhale and exhale breaths rapidly through both the nostrils with a buzzing sound that is similar to the buzzing of bumble bee (Nasal snoring is more difficult.). Keep on doing this exercise till you sweat profusely. End the exercise with inhaling the breath through nostrils as deeply as possible and hold it as long as you can. Then exhale through both the nostrils. As you increase the speed of inhalation and exhalation of breath, In the beginning, heat of the body is increased as the circulation of blood is quickened. In the end the body-heat is decreased by perspiration and you will have amusing and joyful  experience.

Benefits of Bhramari Pranayama: 

The mood feels elevated, with increased flow of knowledge and the asceticism begins to appear.

By success in this Bhramari Kumbhaka the Yogic student gets success in Samadhi.

Note:
Without practicing Anulom-Vilom Pranayama first, This Pranayama would not yield desired benefits.

Essential of  Pranayama

KINDS OF PRANAYAMA
Pranayama is Practice only after purifying Nadis

Nadi Shodhan Pranayama

KapalBhati (Glowing of Skull)
 Among the many kinds of Pranayama. i.e. Kumbhaka, eight kinds are considered as main. These are

Surya Bhedan Pranayama,

Ujjayi Pranayama,

Sitkari Pranayama,

Shitali Pranayama,

Bhastrika Pranayama,

Bhramani Pranayama,
Murchha Pranayama and

Plavini Pranayama

Also read from Kundalini Yoga-SRI SWAMI SIVANANDA

  Research

Acute effect of Mukh bhastrika (a yogic bellows type breathing) on reaction time.