Tagalog Newspaper Reader and a Brief Grammar of Tagalog
Sound Changes Within A Word (Morphophonemic Alternations)
Lavaro, Lorraine Joy. "Some Phonological Constraints in Tagalog"

1. VOWEL LOSS <VL>
bigay + -an			bigyan
bili + -in				bilhin
bukas + -an			buksan
dala + -in				dalhin
kamit + ma--an			makamtan
kinig + pa--an			pakinggan
gawa' + -in			gawin
lagay + -an			lagyan
masid + CinV--an		minamasdan
sakay + -an			sakyan
sakit + na--an			nasaktan
sara + -an				sarhan
sunod + -an			sundan

2. VOWEL LOSS PLUS CONSONANT LOSS (USUALLY GLOTTAL STOP) <VL+CL>
ka'in + -in			kanin
simula' + -an			simulan

3. ADDITION OF N TO THE ROOT = N-INSERTION BEFORE SUFFIX <+N>
kilala + -in			kilalanin
kuha + -in				kunin
halili + -an +M			halinhan 'be relieved'
pa'a  + -an			pa'anan 'on the feet'
sarili' + -in			sarilinin
sarili' + ka--an +M		kasarinlan
talo 'vicorious'		talunan 'loser' [Bloomfield]
tawa + -an				tawanan 'be laughed at'
tawa + pag--anin		pagtawanin 'be amused'
ulo  'head' + -an		ulunan 'on the head'

4. NASAL SUBSTITUTION = NASAL CHANGE + CONSONANT LOSS <NG+CL>
m/b	bahala' + paNG--an	pamahala'an
m/b	bayan + maNGVNG-	mamamayan
m/b	bayani + naNGVNG-	namamayani
m/b	buhay + maNG-		mamuhay
m/p	palo' + maNG-		mamalo'
m/p	pili' + maNGVNG-	mamimili'
m/p	pahinga + paNGVNG-	pamamahinga
n/d	da'ig + maNG-		mana'ig
n/s	salita' + paNGVNG-	pananalita'
n/s	sa'uli' + paNGVNG-	panana'uli'
n/s	sira' + ma- + paNG-	pananira'
n/s	silbi + naNGVNG--an	paninilbihan
n/t	tagumpay + paNGVNG-	pananagumpay
n/t	tali' + paNG-		panali'
n/t	talo + paNG-		panalo
n/t	tawag + naNG--an	panawagan
n/t	tiwala' + p<in>aNGVNG--an	pinaniniwala'an
n/t	tiyak + paNGVNG-	paniniyak
ng/'	'aso + maNG-		mangaso
ng/k	kahoy + paNGVNG-	pangangahoy
ng/k	kahulugan + naNGVNG-	nangangahulugan
ng/k	ka'ilangan + maNGVNG-	manganga'ilangan
ng/k	kalakal + maNGVNG-	mangangalakal
ng/k	kontra + paNG-		pangontra

5a.  INSTRUMENTAL ADJECTIVES = NASAL ASSIMILATION <NG/a>
m/b	bansa + pang-		pambansa
m/b	bata' + pang-		pambata'
n/d	da'igdig + pang-	panda'igdig
n/l	labas + pang-		panlabas
n/s	samantala + pang-	pansamamtala

5b.  THE PREFIX SING- = NASAL ASSIMILATION <NG/a>
ng/s	bilis + (ka)sing-	(ka)simbilis

5c.	  THE PREFIX SANG- 'one' = NASAL ASSIMILATION <NG/a>
ng/d	dali' + sang-		sandali'
ng/l	libo + sang-		sanlibo

6.  WORD FINAL -H <+H>
Tagalog words are neither spoken or written with the glottal fricative [h] word finally. However, an h does appear, when the suffixes -in or -an are attached to a root ending in a vowel (non-glottal stop). Notice the h insertion with the following suffixed roots
+h	basa 'read' + CV--in	babasahin 'reading materials'
+h	sama 'accompany'	samahan 'be accompanied'
+h	gulo 'confusion'	guluhin  'confuse s.ol'

7.  D AND R INTERCHANGE <D/R>
d/r	dating			darating
d/r	damay				makiramay
d/r	dapat				karapatan
d/r	hubad				hubaran

8.  PALATALIZATION <+Y>
The dental obstruents [t], [d], and [s] palatalize to [ch], [j], and [sh] respectively, before a palatal glide [y] or its orthographic equivalent [an unstressed vowel i followed by the glide y] 
t/y	tiyan 'stomach'		chan
s/y	siya  'he/she'		sha
d/y	dyus  'juice'		jus
d/y	diyos 'God'		jos
d/y	diyeta 'diet'		je:ta
d/y	diyan 'there'		jan

They do not palatalize before a stressed vowel [i]
t/i	tíya ‘aunt’		tí:.ya

9.  METATHESIS = sound switching  <M>
In some instances, after vowel loss occurs, certain consonant clusters will metathesize (switch places):
'/n	'alay + i-<in>		inialay
'/n	'ulat + i-<in>		iniulat
'/n	ha'in + i-<in>		iniha'in
h/n	halili + -an +M		halinhan 'be relieved'
n/l	sarili' + ka--an +M	kasarinlan
n/l	lunod + ka--an		kanluran
n/m	tanim + -an +M		tamnan 'be planted'
t/p	atip 'roof'		aptan 'have a roof put on'


The infix <in> metathesizes to ni- before an <l> lateral, <r> rhotic, or y:  <NI>
in/ni	laba' + -an +M		nilaba'an
in/ni	laba + -an			nilabahan
in/ni	linaw + <in>		nilinaw
in/ni	luto' +M			niluto
in/ni	retoke + <in>		niretoke
in/ni	yakap + <in>		niyakap

10. O AND U ALTERNATION  <O/U>
o/u	busog + -in		busugin
o/u	durog + -in		durugin
o/u	gulo' 'commotion'	guluhin 'be troubled or molested'
o/u	hulog + -an		hulugan
o/u	tapos 'finish' + -in	tapusin 'finish it!'
o/u	tulog 'sleep' + -an	tulugan

11. IMPORTANCE OF ACCENT IN DETERMININGDERIVATIONS AND WORDS <AC>
Accent (including vowel length) plays a very important role in Tagalog as it can determine completely different words or derivations.
DERIVATION CHANGES due to accent <AC-d>
kaibigan [ka.’i.bí:.gan]	‘friend’ (penultimate)
kaibigán [ka.’i.bi.gán]	‘desire; preference’ (final)
káibigán [ká:.’i.bi.gán]	‘mutual consent’ (final + antepenultimate)
kaíbigan [ka.’í:.bí:.gan]	‘sweetheart’ (penultimate + antepenultimate)

LEXICAL CHANGES due to accent <AC-l>
baga [bá:.ga]		‘glowing ember’ (penultimaten accent)
bagá [ba.gá]		‘interrogative particle’ (final accent)
bagà [bá:.ga’]		‘lung’ (penultimate accent + glottal stop)
bagâ [ba.gá’]		‘breast tumor’ (final accent + glottal stop)