Monotone chanting

In the Ghitassara Sutta, the Buddha teaches:

Bhikkhus, there are five dangers of reciting the Dhamma with a musical intonation. What five?
Oneself gets attached to the sound, others get attached to the sound, householders are annoyed, saying, “Just as we sing, these sons of the Sakyan sing”, the concentration of those who do not like the sound is destroyed, and later generations copy it.
These, monks, are the five dangers of reciting the Dhamma with a musical intonation.

Bhikkhus, there are these five dangers when Dhamma is chanted with a long, singing sound: 1) He is pleased with himself regarding that sound, (= pride) 2) others are pleased regarding that sound (they have regard for it but not for Dhamma) 3) householders look down upon him (as music is for those who enjoy sense-pleasures) 4) while trying for accuracy of sound his concentration is broken, (he neglects the meaning of what he is chanting) 5) people coming after fall into views (by emulation) ("saying: Our teachers and preceptors sang it thus" [Commentary] — a source of both pride and quarreling among later generations of Buddhists). — Vinaya Pitaka, ii. 108