diff --git a/src/include/espeak-ng/speak_lib.h b/src/include/espeak-ng/speak_lib.h
index cc1e35e7..14500f69 100644
--- a/src/include/espeak-ng/speak_lib.h
+++ b/src/include/espeak-ng/speak_lib.h
@@ -201,7 +201,7 @@ ESPEAK_API int espeak_Initialize(espeak_AUDIO_OUTPUT output, int buflength, cons
 
    buflength:  The length in mS of sound buffers passed to the SynthCallback function.
             Value=0 gives a default of 60mS.
-            This paramater is only used for AUDIO_OUTPUT_RETRIEVAL and AUDIO_OUTPUT_SYNCHRONOUS modes.
+            This parameter is only used for AUDIO_OUTPUT_RETRIEVAL and AUDIO_OUTPUT_SYNCHRONOUS modes.
 
    path: The directory which contains the espeak-ng-data directory, or NULL for the default location.
 
@@ -235,7 +235,7 @@ int SynthCallback(short *wav, int numsamples, espeak_EVENT *events);
       sometimes be zero (which does NOT indicate end of synthesis).
 
    events: an array of espeak_EVENT items which indicate word and sentence events, and
-      also the occurance if <mark> and <audio> elements within the text.  The list of
+      also the occurrence if <mark> and <audio> elements within the text.  The list of
       events is terminated by an event of type = 0.
 
 
diff --git a/src/libespeak-ng/compiledata.c b/src/libespeak-ng/compiledata.c
index dd6247fa..3b08121b 100644
--- a/src/libespeak-ng/compiledata.c
+++ b/src/libespeak-ng/compiledata.c
@@ -857,7 +857,7 @@ static int NextItemMax(int max)
 
 static int NextItemBrackets(int type, int control)
 {
-	// Expect a parameter inside parantheses
+	// Expect a parameter inside parentheses
 	// control: bit 0  0= need (
 	//          bit 1  1= allow comma
 
diff --git a/src/libespeak-ng/dictionary.c b/src/libespeak-ng/dictionary.c
index 8a10cedf..1b914f9e 100644
--- a/src/libespeak-ng/dictionary.c
+++ b/src/libespeak-ng/dictionary.c
@@ -613,7 +613,7 @@ const char *GetTranslatedPhonemeString(int phoneme_mode)
 		for (p = phon_buf2; *p != 0;) {
 			p += utf8_in(&c, p);
 			if (use_tie != 0) {
-				// look for non-inital alphabetic character, but not diacritic, superscript etc.
+				// look for non-initial alphabetic character, but not diacritic, superscript etc.
 				if ((count > 0) && !(flags & (1 << (count-1))) && ((c < 0x2b0) || (c > 0x36f)) && iswalpha(c))
 					buf += utf8_out(use_tie, buf);
 			}
@@ -663,7 +663,7 @@ static int LetterGroupNo(char *rule)
 	 * Returns number of letter group
 	 */
 	int groupNo = *rule;
-	groupNo = groupNo - 'A'; // substracting 'A' makes letter_group equal to number in .Lxx definition
+	groupNo = groupNo - 'A'; // subtracting 'A' makes letter_group equal to number in .Lxx definition
 	if (groupNo < 0)         // fix sign if necessary
 		groupNo += 256;
 	return groupNo;
@@ -2310,7 +2310,7 @@ int TranslateRules(Translator *tr, char *p_start, char *phonemes, int ph_size, c
 						// is it a bracket ?
 						if (letter == 0xe000+'(') {
 							if (pre_pause < tr->langopts.param2[LOPT_BRACKET_PAUSE])
-								pre_pause = tr->langopts.param2[LOPT_BRACKET_PAUSE]; // a bracket, aleady spoken by AnnouncePunctuation()
+								pre_pause = tr->langopts.param2[LOPT_BRACKET_PAUSE]; // a bracket, already spoken by AnnouncePunctuation()
 						}
 						if (IsBracket(letter)) {
 							if (pre_pause < tr->langopts.param[LOPT_BRACKET_PAUSE])
@@ -3018,7 +3018,7 @@ int RemoveEnding(Translator *tr, char *word, int end_type, char *word_copy)
 	int len;
 	char ending[50] = {0};
 
-	// these lists are language specific, but are only relevent if the 'e' suffix flag is used
+	// these lists are language specific, but are only relevant if the 'e' suffix flag is used
 	static const char *add_e_exceptions[] = {
 		"ion", NULL
 	};
diff --git a/src/libespeak-ng/event.c b/src/libespeak-ng/event.c
index 135ec112..acf3a39e 100644
--- a/src/libespeak-ng/event.c
+++ b/src/libespeak-ng/event.c
@@ -16,7 +16,7 @@
  * along with this program; if not, see: <http://www.gnu.org/licenses/>.
  */
 
-// This source file is only used for asynchronious modes
+// This source file is only used for asynchronous modes
 
 #include "config.h"
 
diff --git a/src/libespeak-ng/event.h b/src/libespeak-ng/event.h
index 5f47e108..240bc075 100644
--- a/src/libespeak-ng/event.h
+++ b/src/libespeak-ng/event.h
@@ -49,7 +49,7 @@ extern "C"
 // Initialize the event component.
 // First function to be called.
 // the callback will be called when the event actually occurs.
-// The callback is detailled in speak_lib.h .
+// The callback is detailed in speak_lib.h .
 void event_init(void);
 void event_set_callback(t_espeak_callback *cb);
 
diff --git a/src/libespeak-ng/fifo.c b/src/libespeak-ng/fifo.c
index 553a9232..dc60cc42 100644
--- a/src/libespeak-ng/fifo.c
+++ b/src/libespeak-ng/fifo.c
@@ -16,7 +16,7 @@
  * along with this program; if not, see: <http://www.gnu.org/licenses/>.
  */
 
-// This source file is only used for asynchronious modes
+// This source file is only used for asynchronous modes
 
 #include "config.h"
 
diff --git a/src/libespeak-ng/intonation.c b/src/libespeak-ng/intonation.c
index 4d1a4965..8cbacad1 100644
--- a/src/libespeak-ng/intonation.c
+++ b/src/libespeak-ng/intonation.c
@@ -431,7 +431,7 @@ static int SetHeadIntonation(SYLLABLE *syllable_tab, TUNE *tune, int syl_ix, int
 
 	pitch_range = (tune->head_end - tune->head_start) << 8;
 	pitch_range_abs = abs(pitch_range);
-	drops = drops_0; // this should be controled by tune->head_drops
+	drops = drops_0; // this should be controlled by tune->head_drops
 	initial = true;
 
 	stage = 0;
@@ -784,7 +784,7 @@ static void CalcPitches_Tone(Translator *tr)
 	PHONEME_TAB *prevw_tph; // remember across word boundary
 	PHONEME_LIST *prev_p;
 
-	int pitch_adjust = 0;    // pitch gradient through the clause - inital value
+	int pitch_adjust = 0;    // pitch gradient through the clause - initial value
 	int pitch_decrement = 0; // decrease by this for each stressed syllable
 	int pitch_low = 0;       // until it drops to this
 	int pitch_high = 0;      // then reset to this
diff --git a/src/libespeak-ng/klatt.c b/src/libespeak-ng/klatt.c
index 35e5d0dd..7fa6d8d1 100644
--- a/src/libespeak-ng/klatt.c
+++ b/src/libespeak-ng/klatt.c
@@ -721,7 +721,7 @@ static void pitch_synch_par_reset(klatt_frame_ptr frame)
 /*
    function SETABC
 
-   Convert formant freqencies and bandwidth into resonator difference
+   Convert formant frequencies and bandwidth into resonator difference
    equation constants.
  */
 
@@ -748,7 +748,7 @@ static void setabc(long int f, long int bw, resonator_ptr rp)
 /*
    function SETZEROABC
 
-   Convert formant freqencies and bandwidth into anti-resonator difference
+   Convert formant frequencies and bandwidth into anti-resonator difference
    equation constants.
  */
 
diff --git a/src/libespeak-ng/klatt.h b/src/libespeak-ng/klatt.h
index 5ffd7ae0..22eccca0 100644
--- a/src/libespeak-ng/klatt.h
+++ b/src/libespeak-ng/klatt.h
@@ -73,7 +73,7 @@ typedef struct {
 	long T0;        /* Fundamental period in output samples times 4 */
 	long nopen;     /* Number of samples in open phase of period    */
 	long nmod;      /* Position in period to begin noise amp. modul */
-	long nrand;     /* Varible used by random number generator      */
+	long nrand;     /* Variable used by random number generator      */
 	double pulse_shape_a; /* Makes waveshape of glottal pulse when open   */
 	double pulse_shape_b; /* Makes waveshape of glottal pulse when open   */
 	double minus_pi_t;
diff --git a/src/libespeak-ng/numbers.c b/src/libespeak-ng/numbers.c
index 05e2d7a3..947ba2af 100644
--- a/src/libespeak-ng/numbers.c
+++ b/src/libespeak-ng/numbers.c
@@ -1704,7 +1704,7 @@ static int LookupNum3(Translator *tr, int value, char *ph_out, bool suppress_nul
 		if (ph_ordinal2[0] != 0) {
 			ix = strlen(buf1);
 			if ((ix > 0) && (buf1[ix-1] == phonPAUSE_SHORT))
-				buf1[ix-1] = 0; // remove pause before addding ordinal suffix
+				buf1[ix-1] = 0; // remove pause before adding ordinal suffix
 			strcpy(buf2, ph_ordinal2);
 		}
 	}
diff --git a/src/libespeak-ng/readclause.c b/src/libespeak-ng/readclause.c
index bfba8e30..68b0157a 100644
--- a/src/libespeak-ng/readclause.c
+++ b/src/libespeak-ng/readclause.c
@@ -394,7 +394,7 @@ static espeak_ng_STATUS LoadSoundFile(const char *fname, int index, espeak_ng_ER
 
 static int LookupSoundicon(int c)
 {
-	// Find the sound icon number for a punctuation chatacter
+	// Find the sound icon number for a punctuation character
 	int ix;
 
 	for (ix = N_SOUNDICON_SLOTS; ix < n_soundicon_tab; ix++) {
diff --git a/src/libespeak-ng/synthesize.c b/src/libespeak-ng/synthesize.c
index 5fc3a42e..80409331 100644
--- a/src/libespeak-ng/synthesize.c
+++ b/src/libespeak-ng/synthesize.c
@@ -104,7 +104,7 @@ static void EndAmplitude(void)
 
 static void EndPitch(int voice_break)
 {
-	// posssible end of pitch envelope, fill in the length
+	// possible end of pitch envelope, fill in the length
 	if ((pitch_length > 0) && (last_pitch_cmd >= 0)) {
 		if (wcmdq[last_pitch_cmd][1] == 0)
 			wcmdq[last_pitch_cmd][1] = pitch_length;
diff --git a/src/libespeak-ng/synthesize.h b/src/libespeak-ng/synthesize.h
index 91c42498..6dca6ff7 100644
--- a/src/libespeak-ng/synthesize.h
+++ b/src/libespeak-ng/synthesize.h
@@ -266,7 +266,7 @@ typedef struct {
 #define INSTN_RETURN         0x0001
 #define INSTN_CONTINUE       0x0002
 
-// Group 0 instrcutions with 8 bit operand.  These values go into bits 8-15 of the instruction
+// Group 0 instructions with 8 bit operand.  These values go into bits 8-15 of the instruction
 #define i_CHANGE_PHONEME 0x01
 #define i_REPLACE_NEXT_PHONEME 0x02
 #define i_INSERT_PHONEME 0x03
diff --git a/src/libespeak-ng/tr_languages.c b/src/libespeak-ng/tr_languages.c
index 427d4d26..eedacea5 100644
--- a/src/libespeak-ng/tr_languages.c
+++ b/src/libespeak-ng/tr_languages.c
@@ -391,7 +391,7 @@ static void SetArabicLetters(Translator *tr)
 
 static void SetCyrillicLetters(Translator *tr)
 {
-	// Set letter types for Cyrillic script languages: bg (Bulgarian), ru (Russian), tt (Tatar), uk (Ukranian).
+	// Set letter types for Cyrillic script languages: bg (Bulgarian), ru (Russian), tt (Tatar), uk (Ukrainian).
 
 	// character codes offset by 0x420
 	static const char cyrl_soft[] = { 0x2c, 0x19, 0x27, 0x29, 0 }; // letter group B  [k ts; s;] -- ь й ч щ
@@ -1461,7 +1461,7 @@ Translator *SelectTranslator(const char *name)
 			tr->letter_bits_offset = OFFSET_TAMIL;
 			tr->langopts.numbers =  NUM_OMIT_1_THOUSAND;
 			tr->langopts.numbers2 = NUM2_ORDINAL_AND_THOUSANDS;
-			tr->langopts.param[LOPT_WORD_MERGE] = 1; // don't break vowels betwen words
+			tr->langopts.param[LOPT_WORD_MERGE] = 1; // don't break vowels between words
 		} else if (name2 == L('m', 'l')) {
 			static const short stress_lengths_ml[8] = { 180, 160,  240, 240,  0, 0,  260, 260 };
 			SetupTranslator(tr, stress_lengths_ml, stress_amps_equal);
diff --git a/src/libespeak-ng/translate.c b/src/libespeak-ng/translate.c
index c61d9058..d4f032e3 100644
--- a/src/libespeak-ng/translate.c
+++ b/src/libespeak-ng/translate.c
@@ -474,7 +474,7 @@ static char *SpeakIndividualLetters(Translator *tr, char *word, char *phonemes,
 	if (spell_word > 2)
 		capitals = 2; // speak 'capital'
 	if (spell_word > 1)
-		capitals |= 4; // speak charater code for unknown letters
+		capitals |= 4; // speak character code for unknown letters
 
 	while ((*word != ' ') && (*word != 0)) {
 		word += TranslateLetter(tr, word, phonemes, capitals | non_initial, current_alphabet);
@@ -1923,7 +1923,7 @@ static int TranslateChar(Translator *tr, char *ptr, int prev_in, unsigned int c,
 			if (final > 0)
 				*insert = final + 0x11a7;
 		} else {
-			// extact the initial and insert the remainder with a null initial
+			// extract the initial and insert the remainder with a null initial
 			c = initial + 0x1100;
 			*insert = (11*28*21) + (medial*28) + final + 0xac00;
 		}
diff --git a/src/libespeak-ng/translate.h b/src/libespeak-ng/translate.h
index 74478d37..a992a62f 100644
--- a/src/libespeak-ng/translate.h
+++ b/src/libespeak-ng/translate.h
@@ -115,7 +115,7 @@ extern "C"
 #define FLAG_LAST_WORD     0x10  // last word in clause
 #define FLAG_EMBEDDED      0x40  // word is preceded by embedded commands
 #define FLAG_HYPHEN        0x80
-#define FLAG_NOSPACE       0x100 // word is not seperated from previous word by a space
+#define FLAG_NOSPACE       0x100 // word is not separated from previous word by a space
 #define FLAG_FIRST_WORD    0x200 // first word in clause
 #define FLAG_FOCUS         0x400 // the focus word of a clause
 #define FLAG_EMPHASIZED    0x800
@@ -299,7 +299,7 @@ typedef struct {
 // bit 1=LANG=cz,bg  don't propagate over [v]
 // bit 2=don't propagate acress word boundaries
 // bit 3=LANG=pl,  propagate over liquids and nasals
-// bit 4=LANG=cz,sk  don't progagate to [v]
+// bit 4=LANG=cz,sk  don't propagate to [v]
 // bit 8=devoice word-final consonants
 #define LOPT_REGRESSIVE_VOICING 4
 
@@ -342,7 +342,7 @@ typedef struct {
 // bit 1: stressed syllable: $alt change [e],[o] to [E],[O],  $alt2 change [E],[O] to [e],[o]
 #define LOPT_ALT 15
 
-// pause for bracket (default=4), pause when annoucing bracket names (default=2)
+// pause for bracket (default=4), pause when announcing bracket names (default=2)
 #define LOPT_BRACKET_PAUSE 16
 
 // bit 1, don't break clause before annoucning . ? !
@@ -443,7 +443,7 @@ typedef struct {
 #define NUM_HUNDRED_AND       0x00000040 // add "and" after hundred or thousand
 #define NUM_SINGLE_AND        0x00000080 // don't have "and" both after hundreds and also between tens and units
 #define NUM_SINGLE_STRESS     0x00000100 // only one primary stress in tens+units
-#define NUM_SINGLE_VOWEL      0x00000200 // only one vowel betwen tens and units
+#define NUM_SINGLE_VOWEL      0x00000200 // only one vowel between tens and units
 #define NUM_OMIT_1_HUNDRED    0x00000400 // omit "one" before "hundred"
 #define NUM_1900              0x00000800 // say 19** as nineteen hundred
 #define NUM_ALLOW_SPACE       0x00001000 // allow space as thousands separator (in addition to langopts.thousands_sep)