Doing in-character voices is a hit or miss prospect for some games, and by no means required in a table-top RPG. As a DM that enjoys doing voices for various NPCs in my world I find this table helpful to develop different inspiration for voice types I might use, and having a reference like this lets me make a quick note so I can be sure to use the same voice next time. I compiled this list from a few descriptions for theater actors around the web and hope you’ll find it useful for your game as well.

d100	Voice
1-2	Nasal – Some of the sound seems to come through the nose.
3-4	Appealing – Shows that you want help, approval, or agreement.
5-6	Breathy – With loud breathing noises.
7-8	Brittle – You sound as if you are about to cry.
9-10	Croaky – Sounds as if they have a sore throat.
11-12	Dead – They feel or show no emotion.
13-14	Disembodied – Voice comes from someone who you cannot see.
15-16	Flat – Spoken in a voice that does not go up and down.
17-18	Fruity – Deep and strong in a pleasant way.
19-20	Grating – Unpleasant and annoying.
21-22	Gravelly – Low and rough.
23-24	Gruff – Rough, low, and speaks in short huffs.
25-26	Guttural – Deep and made at the back of your throat.
27-28	Half Singing – Lyrical, light and whimsical
29-30	High Pitched – Very high and shrill.
31-32	Hoarse – Low rough and strained.
33-34	Honeyed – Falsely sweet voice.
35-36	Husky – Low, rumbling and easy.
37-38	Lisp – Drags some consonant sounds with their tounge.
39-40	Low – Quiet and difficult to hear / in a deep voice.
41-42	Matter of fact – blunt and flat.
43-44	Modulated – Controlled and pleasant to listen to.
45-46	Monotonous – Boring because it does not change in loudness or become higher or lower.
47-48	Orotund – Loud and clear.
49-50	Penetrating – So high or loud that it makes you uncomfortable.
51-52	Plummy – This word shows that you dislike people who speak like this.
53-54	Quietly – In a quiet voice.
55-56	Raucous – Loud and sounds rough.
57-58	Ringing – very loud and clear.
59-60	Rough – Not soft and is unpleasant to listen to.
61-62	Shrill – Very loud, high, and unpleasant.
63-64	Silvery – Clear, light, and pleasant.
65-66	Singsong – Rises and falls in a musical way.
67-68	Slurred – Slow or lagging speach pattern.
69-70	Small – A small voice or sound is quiet.
71-72	Smoky – Sexually attractive in a slightly mysterious way.
73-74	Softly Spoken – A quiet gentle voice.
75-76	Sotto Voce – A very quiet voice.
77-78	Stentorian – Loud and severe.
79-80	Strangulated – One that someone stops before they finish making it.
81-82	Strident – Loud and unpleasant.
83-84	Taut – Shows someone is nervous or angry.
85-86	Thick – Voice sounds less clear because of an emotion.
87-88	Thin – High and unpleasant to listen to.
89-90	Throaty – Low and seems to come from deep in your throat.
91-92	Tight – Shows that you are nervous or annoyed.
93-94	Toneless – Does not express any emotion.
95-96	Tremulous – It is not steady because you are afraid or excited.
97-98	Wheezy – Has difficulty breathing.
99-100	Wobbly – Unstable tone due to fright or emotions.