Yes, I believe chanting can help some people with their mental development. Firstly, you need to know what the word chanting means. Chanting is traditionally done at Monasteries morning and evening and also at most ceremonies. The monks and often the lay people will chant in Pail, either in unison or alternately. In Thailand it's sometimes the Pali language and some Thai. I learnt chanting in the West and we alternated between Pali and English.
What is the chanting about? It's usually words from Scriptures. Traditionally there's always a chant for the Buddha, the Dhamma and the Sangha, standard words that are used throughout the world. There's often a chant about death coming, sickness coming, impermanence and Dukkha. There's often a chant about we're the owner of our own Kamma. Sometimes they will actually chant an entire Sutta, for example there's a chant for lovingkindness and compassion. So that's actually what chanting is. Chanting, is a concentrated form of reflective meditation. We're putting in wise thoughts, we're reciting them in a traditional, recognizable rhythm as well just chanting. We're thinking wise, clear, truthful and good thoughts. By chanting them, we're training our minds to think wisely.
Now some of you know about the 20 Suttas that I prepared as a free e-mail book. The assistants here are learning not to chant them, but recite them as reciting is actually the same sort of word for chanting. They're learning to recite them, and to memorize them. Now what happens when you memorize an entire bit of teaching? It's with you everywhere you go. You don't have to grab the book, you've got it inside. When it's in there, isn't that going to help your mental development, as the question says? Absolutely because for one, you can't get away from the teachings so easily, like some of you who come to the retreat to learn a bit, then you go back home and you lose the practice after a few months. You come for another retreat, you get charged up, you go back home you lose it after awhile. When you've memorized the teaching, it's in there for a long time. This is very helpful.
For a lot of people they enjoy chanting with Pali words though if you don't know what it means, I encourage you to always learn what the chant does mean in English, German or what ever. Always find out what it means, because if you actually don't know what it means then chanting can just be a replacement for music to a certain extent. Which in its own way is not so bad, but as to actually developing wisdom, it would be limited. So if you learn the chants and you like the sound of the chanting, which is also very melodious at times, then to learn what the chant actually means will help you with your mental development.