The answer is NO!
I begin 2008 with a confession – I have used the hum in my own vocalizing and teaching in the past. Indeed it has been and continues to be used in many 20th and 21st century studios. The hum however, is not part of the true bel canto approach to technique. The hum originates in the ‘placement’ and ‘singing in the mask’ theories (humming or using nasalized sounds is supposed to place the voice forward and in the mask) and one of the main culprits for the emergence of these ideas was Jean de Resque.
Lamperti on the other hand said to his students, “Don’t hum”! His biographer, William Earl Brown says, “When Lamperti said, ‘Singing is humming with the mouth open’, he did not mean that humming with the mouth closed would bring this about! ‘If you cannot sing with the mouth open, you cannot with it closed’, he would exclaim. ‘You cannot hum right, until you can sing right…Don’t hum!’ He believed that humming fatigued the voice.
Humming may be of some temporary use if a student is using pressed phonation as it can encourage them to ease off, but why not work on the source of the problem at the cords, the start of the note.
My own teacher said ‘Don’t hum!’ in my second lesson with him when he walked into the room and caught me in the middle of doing a quick warm-up on humming exercises. It encourages the larynx to lift so no humming – sorry Pooh!
