Rudra Namakam and Chamakam should be recited only with Swaram. Books are available in Net with Swaram. However, if you want to practice with the help of Audio, it shall be OK.
In the last you shall follow the following mantra which neutralizes the bad affects of "apaswaram".
Yadakshara Padabrashtam matrahenam tu yadbhavet,
tatsarvam kshamyatam deva narayana namo stute
visarga bindu matrani pada paadaaksharani cha
nunaatiriktam yatkinchidabhihi girbhirudeerayet
abhirgirbhiryadato na oona mapyaya harivo vardhamanaha
yada stotrabhyo mahi gotra rujasi bhuistabhajo adha te syama brahma
pravadishma tanno ma haaseet
Om Shantih Shantih Shantihi