The best tones of the speaking voice are the middle and low keys.  These should be used exclusively in daily conversation.  The use of high pitch is due to habit or temperament, but may be overcome through judicious practice.  The objection to a high-keyed voice is not only that it is disagreeable to the listener, but puts the speaker “out of tune” with his audience.

A good speaking voice should possess the qualities of purity, resonance, flexibility, roundness, brilliancy, and adequate power.  These qualities can be rapidly developed by daily reading aloud for ten minutes, giving special attention to one quality at a time.  A few weeks, assiduous practice will produce most gratifying results.  The voice grows through use, and it grows precisely in the way it is habitually used.

Distinct articulation and correct pronunciation are indications of cultivated speech.  Pedantry should be avoided, but every aspirant to correct speech should be a student of the dictionary.  A writer has given this good counsel: 

“Resolve that you will never use an incorrect, an inelegant, or a vulgar phrase or word, in any society whatever.  If you are gifted with wit, you will soon find that it is easy to give it far better point and force in pure English than through any other medium, and that brilliant thoughts make the deepest impressions when well worded.  However great it may be, the labor is never lost which earns for you the reputation of one who habitually uses the language of a gentleman, or of a lady.  It is difficult for those who have not frequent opportunities for conversation with well-educated people, to avoid using expressions which are not current in society, although they may be of common occurrence in books.  As they are often learned from novels, it will be well for the reader to remember that even in the best of such works dialogues are seldom sustained in a tone which would not appear affected in ordinary life.  This fault in conversation is the most difficult of all to amend, and it is unfortunately the one to which those who strive to express themselves correctly are peculiarly liable.  Its effect is bad, for though it is not like slang, vulgar in itself, it betrays an effort to conceal vulgarity.  It may generally be remedied by avoiding any word or phrase which you may suspect yourself of using for the purpose of creating an effect.  Whenever you imagine that the employment of any mere word or sentence will convey the impression that you are well informed, substitute for it some simple expression.  If you are not positively certain as to the pronunciation of a word, never use it.  If the temptation be great, resist it; for, rely upon it, if there be in your mind the slightest doubt on the subject, you will certainly make a mistake.  Never use a foreign word when its meaning can be given in English, and remember that it is both rude and silly to say anything to any person who possibly may not understand it.  But never attempt, under any circumstances whatever, to utter a foreign word, unless you have learned to pronounce correctly the language to which it belongs.”